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Entity Framework Tutorial Joydip Kanjilal

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Entity Framework Tutorial Learn to build a better data access layer with the ADO.NET Entity Framework and ADO.NET Data Services Joydip Kanjilal BIRMINGHAM - MUMBAI
Entity Framework Tutorial Copyright © 2008 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, Packt Publishing, nor its dealers or distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: October 2008 Production Reference: 1201008 Published by Packt Publishing Ltd. 32 Lincoln Road Olton Birmingham, B27 6PA, UK. ISBN 978-1-847195-22-7 www.packtpub.com Cover Image by Vinayak Chittar (vinayak.chittar@gmail.com) [FM-2]
Credits Author Joydip Kanjilal Reviewers Bogdan Brinzarea-Iamandi Stefan Turalski Senior Acquisition Editor Douglas Paterson Development Editor Ved Prakash Jha Technical Editor Ajay Shanker Editorial Team Leader Mithil Kulkarni Project Manager Abhijeet Deobhakta Project Coordinator Lata Basantani Indexer Monica Ajmera Proofreader Joel T. Johnson Production Coordinator Aparna Bhagat Cover Work Aparna Bhagat [FM-3]
About the Author Joydip Kanjilal is a Microsoft MVP in ASP.NET. He has over 12 years of industry experience in IT with more than 6 years in Microsoft .NET and its related technologies. He has authored many articles for some of the most reputable sites like, www.asptoday.com, www.devx.com, www.aspalliance.com, www.aspnetpro.com, www.sql-server-performance.com, www.sswug.com, etc. Several of these articles have been featured at www.asp.net—Microsoft's Official Site on ASP.NET. Joydip was also a community credit winner at www.community-credit.com a number of times. He is currently working as a Senior Consultant in a reputable company in Hyderabad, INDIA. He has years of experience in designing and architecting solutions for various domains. His technical strengths include C, C++, VC++, Java, C#, Microsoft .NET, Ajax, Design Patterns, SQL Server, Operating Systems, and Computer Architecture. Joydip blogs at http://aspadvice.com/blogs/joydip and spends most of his time reading books, blogs, and writing books and articles. His hobbies include watching cricket and soccer and playing chess. Writing a book is always a rewarding experience. My special thanks to Douglas Paterson for providing me the opportunity to author this book—turning this idea into a reality. I am also thankful to the entire Packt team for their support. I am also thankful to Abhishek Kant (Microsoft), Steve Smith (AspAlliance), Russell Jones(DevX), Steve Jones(SSWUG), Jude Kelly (SQL Server Performance), and Anand Narayaswamy (AspAlliance) for their inspiration and support. My heartiest thanks to my friends Tilak and Vinod for their continued encouragement. My deepest respects and gratitude to my parents for their love, blessings, and encouragement. My thanks to my other family members too, for their support, and to little Jini in particular, for her continued inspiration and love. Thank you all so much! [FM-4]
About the Reviewer Bogdan Brinzarea-Iamandi has a strong background in Computer Science holding a Master and Bachelor Degree at the Automatic Control and Computers Faculty of the Politehnica University of Bucharest, Romania. He also holds an Auditor diploma at the Computer Science department at Ecole Polytechnique, Paris, France. His main interests cover a wide area from embedded programming, distributed and mobile computing, and new web technologies. Currently, he is employed as Supervisor within the team of Alternative Channels Sector of the IT Division in Banca Romaneasca, a Member of the National Bank of Greece. He is Project Manager for Internet Banking and he coordinates other projects related to new technologies and applications to be implemented within the banking area. Bogdan is also the author of two AJAX books, the popular AJAX and PHP: Building Responsive Web Applications and Microsoft AJAX Library Essentials, also by Packt. [FM-5]
Table of Contents Preface 1 Chapter 1: Introducing the ADO.NET Entity Framework 7 What You should Know 8 Looking Back 8 What is ADO.NET Entity Framework? 9 Is It Just Another ORM? 9 The ADO.NET Entity Framework Architectural Components 10 The Entity Data Model (EDM) 10 How is the Entity Data Model Represented? 13 The Object Model (O-Space) 15 LINQ to Entities 15 Entity Client 16 Entity SQL 16 Avoiding Complex Joins 17 The Object Services Layer 18 ADO.NET Entity Framework—Features and Benefits at a Glance 19 Installing the Prerequisites 20 Installing the ADO.NET Entity Framework and Its Tools 20 Downloading the Software 20 Installing the Software 21 Designing the Payroll Database 29 Summary 35 Glossary 35 Chapter 2: Getting Started 37 Creating an Entity Data Model 37 Creating the Payroll Entity Data Model Using the ADO.NET Entity Data Model Designer 38 Creating the Payroll Data Model Using the EdmGen Tool 47 The ADO.NET Entity Data Source Control 51
Table of Contents [ ii ] Implementing Our First Application Using the Entity Framework 54 Summary 57 Chapter 3: Entities, Relationships, and the Entity Data Model 59 Entities, Entity Types, and Relationships in the ADO.NET Entity Data Model (EDM) 59 What is an Entity? 60 Defining Entity Sets in the Entity Data Model 60 Extending the Existing Entity Types to Create Derived Entity Types 61 Association Sets, Associations, Containment, and Multiplicity 62 What are Entity Containers? 63 Exploring the Payroll Entity Data Model 64 The Mapping Details Window 65 The Entity Model Browser 67 The Entity Data Model Layers 68 The CSDL Schema 69 The SSDL Schema 75 The MSL Schema 80 Summary 84 Chapter 4: Working with Stored Procedures in the Entity Data Model 85 Mapping Stored Procedures to Functions in the EDM 85 Mapping Create, Update, and Delete Functions to Entities in the EDM 89 Mapping the Association Sets Consistently 93 Mapping Stored Procedures with No Entity Set 99 Using Stored Procedures 100 Mapping Stored Procedures that Return Custom Entity Types 101 Summary 102 Chapter 5: Working with Entity Client and Entity SQL 103 An Overview of the Entity SQL Language 104 From Transact SQL (T-SQL) to Entity SQL (E-SQL) 104 Why Entity SQL When I Already have LINQ to Entities? 105 Features of Entity SQL 105 Operators in Entity SQL 106 Arithmetic Operators 106 Comparison Operators 107 Logical Operators 107 Reference Operators 108 Type Operators 108 Set Operators 108 Operator Precedence 109 Expressions in Entity SQL 109 Query Expressions in Entity SQL 109
Table of Contents [ iii ] Identifiers, Variables, Parameters, and Types in Entity SQL 110 Row 111 Collection 111 Reference 112 Canonical Functions in Entity SQL 113 Mathematical Functions 113 Aggregate Functions 113 String Functions 114 Bitwise Functions 114 Date and Time Functions 115 Data Paging Using Entity SQL 115 Working with the ADO.NET Entity Client 116 Let's Get into Action 117 Building the Connection String 117 Creating an Entity Connection 118 Opening the Connection 118 Executing Queries Using the Entity Command 119 Closing the Connection 121 Other Operations with Entity SQL 123 Inserting a Record Using Entity SQL 123 Inserting a Record with a Foreign Key Constraint 124 Retrieving Native SQL from EntityCommand 124 Transaction Management in Entity SQL 125 Summary 126 Chapter 6: Working with LINQ to Entities 127 Introducing LINQ 127 Why LINQ? 128 Understanding the LINQ Architecture 128 LINQ to XML 129 LINQ to SQL 129 LINQ to Objects 130 LINQ to Entities 131 Querying Data Using LINQ to Entities 131 LINQ to Entities and Entity Framework 131 Differences between LINQ to Entities and LINQ to SQL 132 Operators in LINQ 133 Aggregation 136 Projections 136 Ordering 137 Quantifiers 137 Restriction 138 Conversion 138 Element 139 Set 139 Querying Data Using LINQ 140
Table of Contents [ iv ] Expressions in LINQ to Entities 143 Constant Expressions 144 Comparison Expressions 144 Initializing Expressions 145 Null Comparisons 146 Navigation Properties 147 Immediate and Deferred Query Execution 148 Improving Performance with Compiled Queries 150 Summary 150 Chapter 7: Working with the Object Services Layer 151 What are Object Services? 151 Features at a Glance 153 A Quick Look at the ObjectContext Class in our Payroll EDM 153 Querying Data as in-Memory Objects 156 Adding, Modifying, and Deleting Objects 156 Attaching and Detaching Objects to and from the Object Context 158 Serializing and De-Serializing Entity Instances 159 Change Tracking and Identity Resolution Using ObjectContext 161 Implementing a Sample Application 162 Creating the Form 162 Implementing a Custom DataContext 164 How is This Accomplished? 167 Inheritance in the Entity Framework 176 Table per Hierarchy 176 Table per Type 177 Implementing Complex Types in the EDM 180 Summary 181 Chapter 8: Introducing ADO.NET Data Services 183 Introducing ADO.NET Data Services 184 How Do ADO.NET Data Services and Web Services Differ? 184 What is Representational State Transfer (REST)? 184 Why Use ADO.NET Data Services? 185 Features at a Glance 185 Prerequisites 186 Exposing Data as a Service Using ADO.NET Data Services 186 Creating an ADO.NET Data Service 187 Using a Relational Database as the Data Source 189 Using Data Sources Other Than a Relational Database 192 Understanding the System.Services.Data Namespace 194 Restricting Access to Resources 196 Working with the ADO.NET Data Service Client Library 197 Generating the Client-Side Entity Classes 198
Table of Contents [ v ] Inserting a Record 198 Updating a Record 199 Deleting a Record 200 Consuming an ADO.NET Data Service Using LINQ 201 Exposing a Stored Procedure as a URI 201 Handling Exceptions in ADO.NET Data Services 202 Batching ADO.NET Data Services Requests to Improve Performance 204 Debugging Your Data Service 204 References 205 Summary 206 Index 207
Preface The ADO.NET Entity Framework, the next generation of Microsoft's data access technology, is an extended Object Relational Mapping (ORM) technology that makes it easy to tie together the data in your database with the objects in your applications. This is done by abstracting the object model of an application from its relational or logical model. It is an extended ORM in the sense that it provides many additional features over an ORM. Some of these features are: Entity Inheritance and Composition Identity Resolution and Change Tracking LINQ Support The Object Service Layer This book is a clear and concise guide to the ADO.NET Entity Framework. Packed with plentiful code examples, this book helps you to learn the ADO.NET Entity Framework and ADO.NET Data Services and build a better data access layer for your application. What This Book Covers Chapter 1 is an introduction to the basics of the ADO.NET Entity Framework (EF), its usefulness, its features, and the benefits. Chapter 2 discusses how you can get started with EF, create an Entity Data Model (EDM), and write a program to query data. Chapter 3 gives a detailed explanation of entities, relationships, and each of the sections of the EDM. Chapter 4 provides a sample application that illustrates how to perform CRUD operations against the EDM. • • • •
Preface [ 2 ] Chapter 5 discusses the Entity SQL query language and how to work with the Entity Client provider. Chapter 6 includes a detailed discussion on LINQ to Entities with many code examples. Chapter 7 provides a detailed discussion on the Object Services Layer and its helpful and useful features. Chapter 8 provides an introduction to ADO.NET Data Services and how it can be used with the EDM to perform CRUD operations. What You Need for This Book To learn the concepts covered in this book, the reader should have a proper understanding and working knowledge of the following: ADO.NET ASP.NET C# To execute the code samples in this book, the following technologies should be installed in your system: Visual Studio 2008 Visual Studio 2008 SP1 SQL Server 2005 Windows XP/Vista/2003 or higher Who This Book is For This book is for C# developers who want an easier way to create their data access layer. You will need to be comfortable with ADO.NET, but you do not need to know anything about the Entity Framework. Along the way we will create some ASP.NET applications, so familiarity with this will be helpful. • • • • • • •
Preface [ 3 ] Conventions In this book, you will find various styles of text that help distinguish between different kinds of information. Let's look at some examples of these styles, and an explanation of their meaning. Code words in text are shown as follows: "We can include other contexts through the use of the include directive." A block of code will be set as follows: <asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName" /> <asp:BoundField DataField="LastName" HeaderText="Last Name" SortExpression="LastName" /> When we wish to draw your attention to a particular part of a code block, the relevant lines or items will be made bold. Note that last two lines of the following code sample: <FunctionImport Name="DeleteEmployee"> <Parameter Name="EmployeeID" Mode="In" Type="Int32" /> <Parameter Name="DepartmentID" Mode="In" Type="Int32" /> <Parameter Name="DesignationID" Mode="In" Type="Int32" /> Any command-line input and output will be written as follows: edmgen /mode:fullgeneration /c:"Data Source=.;Initial Catalog=Payroll;User ID=sa;Password=joydip1@3;" /p:Payroll New terms and important words are introduced in a bold-type font. Words that you see on the screen, in menus or dialog boxes for example, appear in our text like this: "clicking the Next button moves you to the next screen". Important notes appear in a box like this with the Notes icon on the left.. Tips and tricks appear like this with the Tips icon on the left.
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Introducing the ADO.NET Entity Framework The ADO.NET Entity Framework is an extended Object Relational Mapping (ORM) technology from Microsoft that abstracts the object model of an application from its relational or logical model. That is, it isolates the object model from the way the data is actually represented in the relational store. This framework makes the conceptual model real by using an extended entity relationship model called the ADO.NET Entity Data Model. This chapter gives you an introduction to the ADO.NET Entity Framework and also equips you with a brief understanding of the related terminologies. We will revisit each of the Entity Framework architectural components as we progress through this book. Our journey of the ADO.NET Entity Framework has just begun! In this chapter, we will cover the following points: An overview of the ADO.NET Entity Framework The ADO.NET Entity Framework Architectural Components Features and benefits of the ADO.NET Entity Framework Installing the ADO.NET Entity Framework But, before we delve deep into this amazing technology from Microsoft, let's take a quick look at the prerequisites for learning the concepts covered in this book. • • • •
Introducing the ADO.NET Entity Framework [ 8 ] What You should Know To learn the concepts covered in this book, the reader should have a basic understanding of the following: Programming using ADO.NET C# Working with ASP.NET Web Applications SQL Server Looking Back Any application has two perspectives. They are the Data Model and the Object Model. While the Data Model defines the way the data is defined and stored, the Object Model defines how the same data will be represented to the user in the presentation layer or, is exposed to the other layers of the application. The Data Model of the application usually deals with the storage and retrieval of the application's data to and from the relational store. The relational store is used for data persistence, consistency, concurrency, and security. It contains the application's data and typically comprises of a set of tables, views, functions, procedures, and the relationships. You typically use T-SQL to query against the relational store which returns result sets that contains columns and rows of data. However, the data returned doesn't necessarily match with the application's object oriented programming model. Usually, we don't use the data returned in the same form in which it is returned from the relational store. We write the necessary code to transform the data returned from the relational store to business objects in the data access layer of the application. Similarly, you need into write code to transform your application's business objects into a form that can be persisted into your relational store. But, what if the schema of the underlying relational store changes? To bridge this apparent mismatch between the data and the object models, ORM tools have evolved. They are used to reduce the code required to transform your application's business objects into a form that can be persisted into the relational store and vice-versa. • • • •
Chapter 1 [ 9 ] What is ADO.NET Entity Framework? The ADO.NET Entity Framework is a type of ORM. It is a development platform that provides a layer of abstraction on top of the relational or logical model. In doing so, it isolates the object model of the application from the way the data is actually stored in the relational store. Developers can use the ADO.NET Entity Framework to program against an object model rather than the logical or relationship model. This level of abstraction is achieved using the Entity Data Model (EDM)—an extended Entity Relationship Model. The EDM reduces the dependency of your domain object model on the database schema of the data store in use. We will discuss more on this topic later in this chapter. Developers can use the ADO.NET Entity Framework to work with domain specific properties such as employee name employee address, contact details, etc, without having to be concerned with how the actual data is stored and represented in the underlying data store. The framework can take care of the necessary translations to either retrieve data from your data store, or, perform inserts, updates, and deletes. Is It Just Another ORM? The ADO.NET Entity Framework is an extended ORM technology from Microsoft. We say it is an extended ORM because it has many additional features compared to a typical ORM. ORMs often use metadata and factory classes to retrieve data or collections of data. On the contrary, using the Entity Framework, you can easily map your data to be accessible in a relational representation in the database to objects, no matter how the mapping is implemented. You can expose different data views to your application without having to change your relational schema. In essence, this allows the applications to have their own view of the data. The applications can even reuse the same views of data amongst themselves. The major difference between the ADO.NET Entity Framework and ORM tools is in the Entity Data Model and the former's ability to query data using strongly typed LINQ. You can even use Entity SQL, a T-SQL like query language for querying the Entity Data Model, to execute dynamic queries. In addition to what a typical ORM framework provides, the ADO.NET Entity Framework provides and supports entity inheritance, entity composition, and a flexible, loosely coupled three tiered model consisting of the conceptual model, the mapping layer, and the storage model. The ADO.NET Entity Framework enables you to even extend the existing schema. In other words, you can extend the generated entity classes to create your own custom entity classes. You can define relationships of any kind such as one-to-one, one-to-many, and even many-to-many. So, isn't it a better ORM?
Introducing the ADO.NET Entity Framework [ 10 ] The ADO.NET Entity Framework Architectural Components The ADO.NET Entity Framework is comprised of the following components: The Entity Data Model LINQ to Entities Entity Client Entity SQL The Object Services Layer The following figure illustrates the layers of the ADO.NET Entity Framework and how they are related to each other: LINQ to Entities Object Services Object Query Entity SQL Entity SQL The Conceptual Model Layer (Defined using .CSDL files) The Mapping Layer (Defined using .MSDL files) The Logical Model Layer (Defined using .SSDL files) Database We will now discuss each of the components of the Entity Framework technology stack in the following sections. The Entity Data Model (EDM) The Entity Data Model, an extended entity relationship model, is the core of the ADO.NET Entity Framework. You can generate an Entity Data Model using the EDMGen.exe command line tool, or, using the ADO.NET Entity Data Model designer—a new Visual Studio template. We will discuss how an Entity Data Model can be generated from a relational schema in the next chapter. • • • • •
Chapter 1 [ 11 ] The following figure illustrates where exactly the Entity Data Model fits in: .NET Objects or collection of .NET Objects The ADO.NET Entity Data Model The Relational Data Store The Entity Data Model abstracts the logical or the relational schema and exposes the conceptual schema of the data using a three-layered approach. It is comprised of the following layers: The Conceptual Data Definition Language Layer (C-Space) The Mapping Schema Definition Language Layer (C-S Space) The Store Space Definition Language Layer (S-Space) The following figure illustrates the layers of the Entity Data Model: The ADO.NET Entity Data Model Layers The Conceptual or the C-Space (GSDL) Comprises of EntityContainer, EntitySets, AssociationSets, Association Types, EntityTypes, Relationships and Functions Queried using Entity SQL or ESQL (EntityConnection, EntityCommand, EntityDataReader) The Mapping Layer or the C-S Mapping Layer (MSL) The Logical or the S-Space (SSDL) Comprises of Tables, Stored Procedures, Views and Functions Queried using ADO.NET Data Providers (SQLConnection, SQLCommand, SQLDataReader, SQLDataAdapter, etc using T-SQL or, using PL-SQL) • • •
Introducing the ADO.NET Entity Framework [ 12 ] The Conceptual Layer or the C-Space Layer is responsible for defining the entities and their relationships. It defines your business objects and their relationships in XML files. The C-Space is modeled using CSDL and is comprised of EntityContainer, EntitySets, AssociationSets, AssociationTypes, EntityTypes, and Functions. You can query this layer using Entity SQL or ESQL (EntityConnection, EntityCommand, and EntityDataReader). The C-S Mapping Layer is responsible for mapping the conceptual and the logical layers. That is, it maps the business objects and the relationships defined in the conceptual layer with the tables and relationships defined in the logical layer. It is a mapping system created in XML, which links or maps the Conceptual and the Logical layers. The C-S Mapping layer is modeled using MSL. The Logical or the Storage Layer (also called the S-Space) represents the schema of the underlying database. This is comprised of tables, stored procedures, view, and functions. It is modeled using SSDL and queried using ADO.NET Data Providers. Hence, we use SQLConnection, SQLCommand, SQLDataReader, and SQLDataAdapter using T-SQL or PL-SQL if our data store is a SQL database. Here is how a typical Entity Data Model looks:
Chapter 1 [ 13 ] How is the Entity Data Model Represented? The Entity Data Model uses the following three types of XML files to represent the C-Space, C-S Space, and the S-Space respectively. .CSDL (Conceptual Schema Definition Language): This represents the C-S Space and is used to map the entity types used in the conceptual model. .MSL (Mapping Schema Language): This represents the C-S Space and is used to map the logical model to the conceptual model. .SSDL (Store Schema Definition Language): This represents the S-Space and is used to map the schema information of the logical layer. If you use the ADO.NET Entity Data Model Designer tool to generate your Entity Data Model, you will have one .edmx file that contains the CSDL, MSL, and SSDL sections bundled into one single file. At runtime, the .csdl, .msl, and .ssdl files are created in the application's output directory. These files store the metadata information as XML for each of the above layers. Here is what the CSDL section of your Entity Data Model looks like: <!-- CSDL content --> <edmx:ConceptualModels> <EntityContainer Name="PayrollEntities"> <EntitySet Name="Designation" EntityType="PayrollModel. Designation" /> </EntityContainer> <EntityType Name="Designation"> <Key> <PropertyRef Name="DesignationID" /> </Key> <Property Name="DesignationID" Type="Int32" Nullable= "false" /> <Property Name="DesignationName" Type="String" Nullable="false" MaxLength="50" Unicode="false" /> <NavigationProperty Name="Employee" Relationship= "PayrollModel.FK_Employee_Designation" FromRole="Designation" ToRole="Employee" /> </EntityType> </edmx:ConceptualModels> • • •
Introducing the ADO.NET Entity Framework [ 14 ] Here is how a typical SSDL section of the Entity Data Model looks like: <!-- SSDL content --> <edmx:StorageModels> <EntityContainer Name="dbo"> <EntitySet Name="Designation" EntityType= "PayrollModel.Store.Designation" /> </EntityContainer> <EntityType Name="Designation"> <Key> <PropertyRef Name="DesignationID" /> </Key> <Property Name="DesignationID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" /> <Property Name="DesignationName" Type="varchar" Nullable="false" MaxLength="50" /> </EntityType> </Schema> </edmx:StorageModels> And here is the C-S maping section for you: <!-- C-S mapping content --> <edmx:Mappings> <Mapping Space="C-S" xmlns="urn:schemas-microsoft-com:windows: storage:mapping:CS"> <EntityContainerMapping StorageEntityContainer="dbo" CdmEntityContainer="PayrollEntities"> <EntitySetMapping Name="Designation"> <EntityTypeMapping TypeName="IsTypeOf(PayrollModel. Designation)"> <MappingFragment StoreEntitySet="Designation"> <ScalarProperty Name="DesignationID" ColumnName= "DesignationID" /> <ScalarProperty Name="DesignationName" ColumnName= "DesignationName" /> </MappingFragment> </EntityTypeMapping> </EntitySetMapping> </EntityContainerMapping> </Mapping> </edmx:Mappings> </edmx:Runtime> </edmx:Edmx>
Chapter 1 [ 15 ] You can also create abstract and complex types in your Entity Data Model. You can derive from an abstract type to create sub-types, but no instance of the abstract type can be created. You can also create complex types. That is, types that don't have any identity of their own. A typical example of a complex type is the Address type. We will skip further discussion on each of the sections of an Entity Data Model until Chapter 3. The Object Model (O-Space) When working with the ADO.NET Entity Framework, you will have an Object Model on top of all the Entity Data Model layers. You need to model the Object Model using .NET objects. The following figure illustrates how the Object Model fits in with the EDM layers: The Object Model or the O-Space The O-C Mapping Layer The Conceptual Model or the C-Space (Modelled using CSDL) The Mapping Layer or the C-S Space (Modelled using MSL) The Logical Model or the S-Space (Modelled using SSDL) The Object Model Layer contains, .NET objects, collection of .NET objects, types, properties and methods. You can use the Object Model or the O-Space Model to query your business objects, or the collections of your business objects, using LINQ to Entities or Entity SQL. The C-Space and O-Space models are actually mapped by the O-C Mapping Layer using code attributes applied to the O-space Model. LINQ to Entities Language Integrated Query (LINQ) is a query translation pipeline that has been introduced as part of the C# 3.0 library. It comprises a set of query operators for different data sources (LDAP, Objects, CSV, XML, Entities, SQL, etc.). It is an extension of the C# language and provides a simplified framework for accessing relational data in a strongly typed, Object Oriented manner.
Introducing the ADO.NET Entity Framework [ 16 ] LINQ to Entities is a Microsoft technology that enables you to query your business objects from within the language in a strongly typed manner. You can use LINQ to Entities, a superset of LINQ to SQL, to query data against a conceptual data model, namely, the Entity Data Model. We will learn more on LINQ and LINQ to Entities in the chapter 6. Here is an example of a typical LINQ to Entities query: PayrollModel.PayrollEntities ctx = new PayrollModel.PayrollEntities(); var query = from emp in ctx.Employee select emp; foreach (var employee in query) Response.Write("<BR>"+employee.FirstName); LINQ to Entities rests on top of the ADO.NET Entity Framework's Object Services Layer and that the LINQ to Entities queries are internally translated to canonical query trees. This, in turn, gets converted internally to corresponding SQL queries in a form expected by your underlying database. Entity Client Entity Client, the gateway to entity-level queries, is the Entity Framework's counterpart of ADO.NET's SQL Client or Oracle Client that uses Entity SQL or E-SQL to query the conceptual model. You create a connection using Entity Connection, execute commands through Entity Commands, and retrieve the result sets as Entity Data Readers. Entity SQL Entity SQL is a data store independent derivative of T-SQL that supports entity inheritance and relationships. You can use it to query data using the conceptual schema. You can even build your own dynamic queries. These E-SQL queries are internally translated to data store dependent SQL queries. This translation, that is, the conversion of the E-SQL queries to their data store-specific query language like T-SQL, (it doesn't need to be only T-SQL, however, it is the supported one) is handled by the Entity Framework. Entity SQL or E-SQL may not be as strongly typed as LINQ is, but, you have the flexibility of executing dynamic queries using it, much like T-SQL.
Chapter 1 [ 17 ] Strongly typed data access is one of the most striking features of LINQ. LINQ queries are checked at compile time. This is unlike SQL queries which are only detected at runtime. But, why do you need Entity SQL when you have LINQ to Entities to query data through you Entity Data Model? You can, using Entity SQL, compose queries that are difficult to determine until the time the query is executed. On a different note, Entity SQL is a full text-based query language that you can use in much the same way as you use ADO.NET data providers. Here is an example that shows how you can use Entity SQL to insert data in your applications. using (EntityConnection conn = new EntityConnection("Name=PayrollEnti ties")) { try { conn.Open(); EntityCommand cmd = conn.CreateCommand(); cmd.CommandText = "PayrollEntities.AddNewEmployee"; cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.AddWithValue("FirstName", "Joydip"); cmd.Parameters.AddWithValue("LastName", "Kanjilal"); cmd.Parameters.AddWithValue("Address", "Hyderabad"); cmd.Parameters.AddWithValue("DepartmentID", 4); cmd.ExecuteNonQuery(); } catch (Exception ex) { Response.Write(ex.ToString()); } } To query data from the Entity Data Model, you have three choices—Entity SQL, LINQ to Entities, and Object Services. Avoiding Complex Joins You can use Entity SQL to avoid complex joins as you will typically be querying against a conceptual model of the data. As an example, if we want to display employee names and the department names in which they work, we would have to join the information of the Employee and the Department tables and then filter the unwanted columns to retrieve only the information that is required. Such traversals become a nightmare as you add additional tables and you therefore require more complex joins.
Introducing the ADO.NET Entity Framework [ 18 ] When you implement your Object Model using Object Oriented Programming Languages, you expose the object's relationships with other objects of its kind using properties. This is in contrast to the approach we just discussed. Hence, designing an Object Model using this approach is cumbersome. This is exactly where the ADO. NET Entity Framework fits in; it represents the conceptual and logical model of data while using grammar that is common to both. Here is a code snippet that explains how you can use Entity SQL to avoid complex joins in your application's code. The following T-SQL query can be used to retrieve employee data split across three tables, namely, Employee, Department, and Salary. Select Employee.FirstName, Employee.LastName, Department. DepartmentName, Salary.Basic from Employee INNER JOIN Department on Department.DepartmentID = Employee.DepartmentID INNER JOIN Salary on Salary.EmployeeID = Employee.EmployeeID And, here is how you will use the Entity SQL to achieve the same result: Select FirstName, LastName, DepartmentName, Basic from EmployeeData The Object Services Layer Apart from querying the Conceptual Model, you might, at some point, have to work with entities such as in-memory objects or a collection of in-memory objects. To do this you need Object Services. You can use it to query data, from almost any data store, with less code. In addition to from enabling you to perform CRUD operations, the Object Services Layer provides the following additional services: Change tracking Lazy loading Inheritance Optimistic concurrency Merging data Identity resolution Support for querying data using Entity SQL and LINQ to Entities We will learn more about Object Services later in the book. The Object Services Layer internally uses an Object Query object for query processing. Note that the Object Services Layer supports querying data using both Entity SQL and LINQ to Entities. • • • • • • •
Chapter 1 [ 19 ] You can query data from the Entity Data Model either using Object Services or Entity Client. However, if you require change tracking, be aware that only Object Services provides this feature. Note that in either case, the ADO.NET Data Providers are responsible for talking to the underlying database. Here is an example that shows how you can use Object Services to retrieve data. using (ObjectContext ctx = new ObjectContext("Name=PayrollEntities")) { var query = from employee in ctx.CreateQuery<PayrollModel. Employee>("PayrollEntities. Employee") select employee; foreach (PayrollModel.Employee emp in query) { Response.Write("<BR>" + emp.FirstName); } } ADO.NET Entity Framework—Features and Benefits at a Glance Here is a quick look at some of the features and benefits of the ADO.NET Entity Framework: Increased level of abstraction. An extensible and flexible provider model. Seamless querying of data using Entity SQL and LINQ. A flexible schema for storing the mapping information. Reduction to the amount of KLOC needed to write data access code in your applications. Provides a layer of abstraction on top of any data store as long as an implementation for the underlying data store is provided. A powerful Object Services Layer. A full text-based query language. Support for a conceptual data model of an application. • • • • • • • • •
Introducing the ADO.NET Entity Framework [ 20 ] KLOC refers to Kilo Lines of Code, a unit of measuring the amount of source code in your programs. Installing the Prerequisites To run the programs given in this book, you should have the following elements installed on your system: Visual Studio.NET 2008 Professional SQL Server 2005 or higher Microsoft .NET Framework 3.5 SP1 ADO.NET Entity Framework Beta 3 or higher ADO.NET Entity Framework Tools December 2007 CTP or higher Installing the ADO.NET Entity Framework and Its Tools Before you proceed with installing EF Beta 3 and its tools, make sure that you have installed Visual Studio.NET 2008 Professional and SQL Server 2005 on your system. I will skip the discussion on installing Visual Studio 2008 Professional and SQL Server 2005 at this time. Downloading the Software Let us take a look at the necessary software that you need to download in order to work with the ADO.NET Entity Framework. Download ADO.NET Entity Framework Beta 3 from the following link: http://www.microsoft.com/downloads/details. aspx?FamilyId=15DB9989-1621-444D-9B18-D1A04A21B519&displaylang =en Download ADO.NET Entity Framework Tools December 2007 CTP from the link give below: http://www.microsoft.com/downloads/details. aspx?FamilyId=D8AE4404-8E05-41FC-94C8-C73D9E238F82&displaylang =en • • • • • • •
Chapter 1 [ 21 ] Download the patch update to Visual Studio.NET 2008 from the link given below: http://go.microsoft.com/fwlink/?LinkID=104985 Download Microsoft .NET Framework 3.5 SP1 from the following link: http://www.microsoft.com/downloads/details. aspx?FamilyId=8C36ACA4-E947-4760-9B05-93CAC04C6F87&displaylang =en Installing the Software Now that the required software has been downloaded, we will now install each one individually. Double-click on the ADO.NET Entity Framework Setup file. The following installation wizard window will appear: Now, click on Next. • •
Introducing the ADO.NET Entity Framework [ 22 ] Here is how the next screen looks like: In the above window that appears, check the checkbox and click on Install. The installation procedure starts and when done, the following screen appears:
Chapter 1 [ 23 ] Click on Finish to complete the installation process. Now that you have installed the ADO.NET Entity Framework successfully on your system, the next step is to install the ADO.NET Entity Framework Tools CTP. But before you do that, you need to install the Visual Studio.NET 2008 patch update. Double-click on the Visual Studio.NET patch update setup file that you downloaded earlier. The following window appears: Now, click on Next.
Introducing the ADO.NET Entity Framework [ 24 ] The following window appears: Check the check box to agree and accept the license terms and click on Next to start the installation process. Once the installation is complete, the following window appears:
Chapter 1 [ 25 ] Click on Finish to complete the installation process. Now, we need to install the ADO.NET Entity Framework Tools CTP. To do this, double-click on the ADO.NET Entity Framework December 2007 Tools CTP you downloaded earlier. The following screen appears:
Introducing the ADO.NET Entity Framework [ 26 ] Click on Next. The following window appears: Now, check the check box to accept the license terms and click on Next. The following window will appear:
Chapter 1 [ 27 ] Click on Install to start the installation process. Once the installation is complete, the following window is displayed: Clink on Finish to complete the installation process. We will now install Microsoft .NET Framework 3.5 SP1. It contains many additional features and most importantly, we need it to work with the Entity Data Source control. We will discuss this control in the next chapter.
Introducing the ADO.NET Entity Framework [ 28 ] To install Microsoft .NET Framework 3.5 SP1 on your system, double-click on the setup file you downloaded earlier. The following screenshot shows the window that will appear: Select the radio button to accept the terms of the license agreement and click on Install to start the installation process.
Chapter 1 [ 29 ] Once the installation process is complete, the following window is displayed: Click on Exit to complete the installation process. You are done! Having installed these prerequisites, we will now design our sample database. We will use this database throughout this book. We will assign the name Payroll to our design database. The next section discusses the design of this sample database. Designing the Payroll Database In this section, we will design our Payroll database, which we will use throughout this book. This database will comprised of the following five tables: Employee Department Designation Salary Provident Fund • • • • •
Introducing the ADO.NET Entity Framework [ 30 ] Here is the script for creating these tables. CREATE TABLE [dbo].[Employee]( [EmployeeID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [LastName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [Address] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [Phone] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [DepartmentID] [int] NOT NULL, [JoiningDate] [datetime] NOT NULL, [LeavingDate] [datetime] NULL, [DesignationID] [int] NOT NULL, CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED ( [EmployeeID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Department]( [DepartmentID] [bigint] NOT NULL, [DepartmentName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [DepartmentHead] [bigint] NOT NULL, CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED ( [DepartmentID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Designation]( [DesignationID] [bigint] NOT NULL, [DesignationName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_ AS NOT NULL, CONSTRAINT [PK_Designation] PRIMARY KEY CLUSTERED ( [DesignationID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Salary]( [SalaryID] [bigint] NOT NULL, [EmployeeID] [bigint] NOT NULL, [Basic] [money] NOT NULL, [Allowance] [money] NOT NULL, [PFID] [bigint] NULL, [Tax] [money] NOT NULL, [GrossSalary] [money] NOT NULL,
Chapter 1 [ 31 ] [NetSalary] [money] NOT NULL, CONSTRAINT [PK_Salary] PRIMARY KEY CLUSTERED ( [SalaryID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[ProvidentFund]( [PFID] [bigint] NOT NULL, [PFAmount] [money] NOT NULL, CONSTRAINT [PK_ProvidentFund] PRIMARY KEY CLUSTERED ( [PFID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] Here is how the database diagram for our Payroll database looks:
Introducing the ADO.NET Entity Framework [ 32 ] We will create some stored procedures now that we will use to insert, update, and delete data from the tables we just created. Here is a list of the stored procedures that we will create for our Payroll database: Employee_Insert Employee_Update Employee_Delete Department_Insert Department_Update Department_Delete Designation_Insert Designation_Update Designation_Delete ProvidentFund_Insert ProvidentFund_Update ProvidentFund_Delete Salary_Insert Salary_Update Salary_Delete Here is the script for these procedures. Create Procedure Employee_Insert As @FirstName varchar(50), @LastName varchar(50), @Address varchar(50), @Phone varchar(50), @DepartmentID int, @DesignationID int, @JoiningDate datetime, @LeavingDate datetime as Insert into Employee(DepartmentID, DesignationID, JoiningDate, LeavingDate) values (@DepartmentID, @DesignationID, @JoiningDate, @LeavingDate) Go Create Procedure Employee_Update @EmployeeID int, @FirstName varchar(50), @LastName varchar(50), @Address varchar(50), @Phone varchar(50), @DepartmentID int, @DesignationID int as Update Employee Set DepartmentID = @DepartmentID, DesignationID = @DesignationID Where Employee.EmployeeID = @EmployeeID • • • • • • • • • • • • • • •
Chapter 1 [ 33 ] Go Create Procedure Employee_Delete @EmployeeID int as Delete from Employee where Employee.EmployeeID = @EmployeeID Go Create Procedure Department_Insert @DepartmentName varchar(50) as Insert into Department (DepartmentName) values (@DepartmentName) Go Create Procedure Department_Update @DepartmentID int,@DepartmentName varchar(50) as Update Department Set DepartmentName = @DepartmentName where DepartmentID = @DepartmentID Go Create Procedure Department_Delete @DepartmentID int as Delete from Department where DepartmentID = @DepartmentID Go Create Procedure Designation_Insert @DesignationName varchar(50) as Insert into Designation (DesignationName) values (@DesignationName) Go Create Procedure Designation_Update @DesignationID int, @DesignationName varchar(50) as Update Designation Set DesignationName = @DesignationName where DesignationID=@DesignationID Go Create Procedure Designation_Delete @DesignationID int as Delete from Designation where DesignationID=@DesignationID Go Create Procedure ProvidentFund_Insert @EmployeeID int, @PFAmount money as Insert into ProvidentFund (EmployeeID, PFAmount) values (@EmployeeID, @PFAmount)
Introducing the ADO.NET Entity Framework [ 34 ] Go Create Procedure ProvidentFund_Update @PFID int, @EmployeeID int, @PFAmount money as Update ProvidentFund set EmployeeID = @EmployeeID, PFAmount = @PFAmount where PFID = @PFID Go Create Procedure ProvidentFund_Delete @PFID int as Delete from ProvidentFund where PFID = @PFID Go Create Procedure Salary_Insert @EmployeeID int, @PFID int, @Basic money, @Allowance money, @Tax money, @GrossSalary money, @NetSalary money as Insert into Salary(EmployeeID, PFID, Basic, Allowance, Tax, GrossSalary, NetSalary) values (@EmployeeID, @PFID, @Basic, @Allowance, @Tax, @GrossSalary, @NetSalary) Go Create Procedure Salary_Update @SalaryID int, @EmployeeID int, @PFID int, @Basic money, @Allowance money, @Tax money, @GrossSalary money, @NetSalary money as Update Salary set EmployeeID = @EmployeeID, PFID = @PFID, Basic = @Basic, Allowance = @Allowance, Tax = @Tax, GrossSalary = @ GrossSalary, NetSalary = @NetSalary where SalaryID = @SalaryID Go Create Procedure Salary_Delete @SalaryID int as Delete from Salary where SalaryID = @SalaryID We will add more tables and stored procedures to our Payroll database as necessary in the chapters to follow.
Chapter 1 [ 35 ] Summary The ADO.NET Entity Framework mainly addressees how easily you can persist and query your data with many of added services. You can use the ADO.NET Entity Framework to focus on the object model rather than the logical model. In other words, you can add a level of abstraction on top of your relational store. In this chapter, we have had a look at what this framework is, its architecture, advantages, and how it differs from LINQ to SQL (formerly called DLINQ). In the next chapter, we will learn how to get started with the ADO.NET Entity Framework. Glossary Entity: This is the core concept in the Entity Framework. An Entity essentially models individual objects, like, employees, customers, etc. It is something that is uniquely definable, distinctly identifiable, and contains information pertaining to the entity. Relational or Logical Model: A relational or logical model depicts the logical view of data that comprises of the normalized entities and their inter-relationships in a database. Object Model: An Object Model may be defined as a collection of the objects, members, and properties of a class and the relationships between them that illustrates the structure of a system. An Object Model of a system is centered on the three basic properties of Object Oriented Programming—encapsulation, abstraction, and inheritance. The Entity Data Model (EDM) is an implementation for the Entity – Relationship model (commonly called the E-R model). It depicts the entities and their relationships. The EDM is a view of the data store that your application will use.
Getting Started In the previous chapter we took a look at the ADO.NET Entity Framework including its architecture and its features. We also designed our Payroll database that we will be using throughout this book to store and retrieve data. We will use the same database in this chapter to generate an Entity Data Model and then use it, along with the Entity Data Source control, to bind data to a GridView data control. In this chapter, we will cover the following points: Creating an Entity Data Model Introducing the Entity Data Source Control Implementing our first application using the ADO.NET Entity Framework We will start this chapter with a discussion on how we can create an Entity Data Model from our Payroll database. Creating an Entity Data Model You can create the ADO.NET Entity Data Model in one of two ways: Use the ADO.NET Entity Data Model Designer Use the command line Entity Data Model Designer called EdmGen.exe We will first take a look at how we can design an Entity Data Model using the ADO. NET Entity Data Model Designer which is a Visual Studio wizard that is enabled after you install ADO.NET Entity Framework and its tools. It provides a graphical interface that you can use to generate an Entity Data Model. • • • • •
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about his family, anything along this line and I don't think I ever discussed my past with him. Mr. Jenner. Was any mention ever made of his attendance at or even the name of the Albert Schweitzer College? Mr. Thornley. No. Mr. Jenner. No discussions about any plans of his or possibility of his seeking further education of any kind or character when he was mustered out of the Marines? Mr. Thornley. None whatsoever. For one thing we were not close enough friends to have any personal interests in each other. I looked upon him as somebody to argue with, another atheist—therefore, without the problem of religion between us—and to argue philosophy and politics about, and I think he looked upon me in about the same light. Mr. Jenner. What was your dexterity with Marine weapons? Mr. Thornley. Mine? Mr. Jenner. Yes. Mr. Thornley. I was a sharpshooter. Mr. Jenner. What was his? Mr. Thornley. I believe—well, at that time I didn't know. Mr. Jenner. You didn't know. I want your viewpoint as of that time. While you were based at El Toro, did the unit engage with any regularity in rifle practice? Mr. Thornley. None whatsoever. At that time, the whole time I was there, we did not engage in rifle practice. Mr. Jenner. As a matter of curiosity on my own part, why was that? Mr. Thornley. Well, in the Marine Corps you are required once a year to go to the rifle range and qualify. I was not there an entire year. Point No. 2, this was the Marine air wing which has much less
of an emphasis on, in general, on rifle practice because it is not going to be utilized in battle, and a much stronger emphasis, in the case of the outfit we were in, on our particular military occupational specialty. Mr. Jenner. Which was? Mr. Thornley. 6749 Aviation Electronic Operator. Mr. Jenner. Was this true when you reached Japan? Mr. Thornley. More so. When I reached Japan, however, we did go to the rifle range one time shortly after I got there, and qualify. I recall at that time that in Japan we weren't even having rifle inspections. There you could put your rifle away in your locker and forget about it, and take it out every couple of months and make sure it hadn't corroded away, and put it back again. Mr. Jenner. But you didn't even have rifle inspection? Mr. Thornley. Once in a while we would have one, but not with any frequency whatsoever. Mr. Jenner. Were you forewarned so that you could clean your rifle? Mr. Thornley. No; usually you were caught unawares, which was why you kept it clean in the locker. Mr. Jenner. I see. What are the grades of marksmanship? Mr. Thornley. Marksman, sharpshooter, and expert. Mr. Jenner. Marksman, sharpshooter, and expert. Therefore, I gather from that that marksman was the basic grade. Mr. Thornley. Yes. Mr. Jenner. A grade that every marine was expected to, and had to, attain that grade? Mr. Thornley. Not had to attain, some didn't, and there was no particular penalty involved, except maybe something a little extracurricular when you were in boot camp. Otherwise, you didn't
wear a marksman's medal is all. You didn't have any qualification in the infantry; of course, it would be looked down upon in the case of promotion or something like that. In the air wing it had much slighter significance than that. Maybe if you were being considered for a meritorious promotion and you hadn't qualified you wouldn't get it, but day to day it had no significance. Mr. Jenner. Were the standards applied in the air wing with respect to qualifications for these three classes as severe or as high as the standards applied, let us say, in the Marine infantry? Mr. Thornley. Exactly the same; yes. Mr. Jenner. Exactly the same. Would you please state for me your concept of the degree of marksmanship for (a) marksman, (b) sharpshooter, (c) expert? Mr. Thornley. Well, a marksman is an average shooter. A man, I think, could pick up a rifle and with a little commonsense and a minimum knowledge of the basics of marksmanship qualify as a marksman. When a man doesn't qualify as a marksman it is usually either because he is nervous on the day of qualification or he is gun shy or some outside influence confuses him; maybe he gets his windage off, something like this. Sharpshooter is just a little above average. It ranges over about —a pretty wide field. But it is a man who—a sharpshooter would be a man, the average man, with a good, maybe a week of training on how to use a rifle, and some practice. Whereas an expert is the kind of man I would hate to have on the other side in a war. He is accurate with his rifle up to and including 500 yards in a number of different positions. Hits the bull's- eye or close to the bull's-eye an overwhelming percentage of the time. Mr. Jenner. Is that the category in which we would place that to which we refer generally as the sniper?
Mr. Thornley. Yes. Well, any man might be assigned as a sniper, I imagine. But an expert rifleman would perform much better. Mr. Jenner. Maybe be a superior sniper. Mr. Thornley. Yes. Definitely. Mr. Jenner. And to attain the position of expert marksman must there be considerable practice and use of the weapon or is it more of natural ability? Mr. Thornley. Now, you enter in once again to natural ability, just as not qualifying might be caused by a lack of natural ability of some kind. An expert rifleman probably would have a much calmer nervous system or, you might say, a much greater degree of control. I would imagine training can make up for this. I know a couple of times I just missed expert by a few points. It seemed that I couldn't make expert. It seemed to me there was just something I didn't have in order to make expert. It was very frustrating. Mr. Jenner. You tried? Mr. Thornley. Yes; it takes a great degree of control, primarily. Of course, the other things like good eyesight and so on and so forth. Mr. Jenner. Oh, yes. Mr. Thornley. Yes. Mr. Jenner. Did you ever discuss with Oswald his degree of proficiency in the use of the rifle? Mr. Thornley. Not to the best of my knowledge. Mr. Jenner. Did you have any impressions that you gathered in that respect while you were with him at El Toro? Mr. Thornley. None whatsoever. Had somebody asked me to guess about Oswald, I would have said, well, he probably didn't qualify, just because that was the type of guy he was, but that is all. Mr. Jenner. You would never have expected him to have been a sharpshooter, for example?
Mr. Thornley. It wouldn't have greatly surprised me if he was and it wouldn't have greatly surprised me if he wasn't. This is something very difficult: to look at a man and tell, at least it is very difficult for me. I have seen some drill instructors who could do it. But to tell whether he is going to be an expert or a sharpshooter, marksman, I am not qualified. Mr. Jenner. While you were stationed with him at El Toro, did you ever go off base with him? Mr. Thornley. No. Mr. Jenner. Did you ever have any discussion of dates? Mr. Thornley. No. Mr. Jenner. His attitude toward women? Mr. Thornley. No. Mr. Jenner. Sex? Mr. Thornley. None whatsoever. Mr. Jenner. Was there any scuttlebutt around the camp in that regard with respect to him? Mr. Thornley. Not to the best of my knowledge. Mr. Jenner. Sex habits, propensities? Mr. Thornley. No; you stand a risk in the Marine Corps, if you are at all quiet and tend to be introverted, of being suspected of being homosexual, but to the best of my knowledge there were never any comments made of this nature. Mr. Jenner. Do you recall some other readings of his in addition to "1984"? Mr. Thornley. I do recall having mentioned Dostoievsky to him and I know he had read something and I think it was "Crime and Punishment" but I am not sure. It was something I had not read by Dostoievsky when I had read about, I guess at that time, about three or four books.
Mr. Jenner. It is a great book. Mr. Thornley. Someday I am going to get around to it. Mr. Jenner. Have you not read it yet? It is a really great book. Mr. Thornley. No; and I don't recall him mentioning any other books offhand. I don't—I can't think of a thing besides "1984" and some book by Dostoievsky. Mr. Jenner. While you were based at El Toro did he engage, did you notice, in any officer baiting on his part with respect, in particular, to such matters as foreign affairs? Mr. Thornley. Yes; not on foreign affairs, no, but the same officer, Lieutenant Donovan, spoke of in a foreign affairs lecture in the newspapers, I do remember him baiting him on a couple of occasions. Mr. Jenner. Oswald attempting to bait Lieutenant Donovan? Mr. Thornley. I don't remember what it was. I know, I believe Lieutenant Donovan was also a lieutenant which I had had a couple of run-ins with if I remember correctly. If not, it was Lieutenant Delprado. It was one of the two of them. Mine were completely accidental and I went to great length to keep away from one of them because it seemed like any time I was around him I happened to do something to irritate him. But Oswald, I don't recall exactly what he said, but he a couple or three times went out of his way to say something to one of these lieutenants that would cause them to be irritated and in this you can't really say that he was exceptional. It happened many times. In Oswald's case though, it was exceptionally—— Mr. Jenner. You mean it happened many times with respect to other noncoms in the Marines with respect to these officers? Mr. Thornley. Right; but in Oswald's case it seemed a little more deliberate. Some guys would get mad and they would say something, or sometimes they would do something by accident, and
they would get themselves involved and then they would decide, "Well, what the hell," and push it all away. Oswald it seemed didn't have to have any reason. He just told an officer to get lost. Mr. Jenner. He baited an officer for the pleasure of it? Mr. Thornley. Yes; I might mention that this was one means by which he won the admiration of others in the outfit in that the junior officers especially are usually disliked, or were in that outfit, and this made him on such occasions as he engaged with an officer in some kind of officer baiting, this won the respect, for at least a few minutes, of the men—who would kind of laugh about it, and chuckle over it and tell others about it. Perhaps this is why he did it. Mr. Jenner. You mentioned some slovenliness on his part; what about his quarters, his barracks; did you have occasion to observe them? Mr. Thornley. I don't think I was ever in his barracks. I do recall having been told that he had Russian books and that is all I—that is the only connection I can make now in my mind with his quarters. I don't think I ever saw them. Mr. Jenner. You already have given us something of his view of the U.S. Marine Corps. Would you give us a summary of that? Give us your impression of his views with respect to the U.S. Marine Corps. Mr. Thornley. Well, definitely the Marine Corps was not what he had expected it to be when he joined. Also he felt that the officers and the staff NCO's at the Marine Corps were incompetent to give him orders. Mr. Jenner. Incompetent in what sense, they were below him intellectually? Mr. Thornley. They were below him intellectually—and for various other reasons in each case, too. Maybe this officer was ignorant, as was brought out about foreign affairs, in Oswald's mind, knew less than Oswald did about it. I don't hold with the stand that Oswald
would study up on foreign affairs simply in order to bait the officer. I think it just happened to be that Oswald would see that the officer was basing his foreign affairs maybe on Time magazine when Oswald had done a little more reading and I think he resented this Time magazine approach to foreign affairs. Mr. Jenner. How did these discussions arise, Mr. Thornley, the discussion of foreign affairs by officers? Mr. Thornley. Well, the officers, every so many weeks—this is mentioned somewhere in this pile of papers—every so many weeks a lieutenant is appointed to give a foreign affairs lecture or a current affairs lecture, pardon me, to the troops, at which time he explains the world situation in a half hour. I remember having one second lieutenant telling us about Dalai Lama or it was a first lieutenant and I forget what he told us, but it was something completely absurd. I think at that time the Dalai Lama had just disappeared or something, and one would get the impression, I think, that he thought the Dalai Lama was a leader in Pakistan or something. Mr. Jenner. That is the impression the lieutenant tried to convey? Mr. Thornley. Well, I think that was the impression the lieutenant had had when he had been assigned to give this lecture. The last minute, he got down and started going through the news magazines to get his information, got it somewhat inaccurately, and didn't particularly care whether it was accurate or not anyway. Stood up in front of the troops and reeled off the lecture, and, of course, most of the enlisted men didn't know enough to criticize him either because they weren't that interested, and that was it—with a couple of people laughing up their sleeves, and this happened later, this didn't happen at the time I knew Oswald. However, in such a situation Oswald would have been careful I am sure to raise his hand and correct the lieutenant. Mr. Jenner. I was going to get to that. During the course of these lectures did the troops as you called them engage in discussion with the instructor?
Mr. Thornley. They were permitted to ask questions, to raise their hands to ask questions. And Oswald would have probably asked a question which would have made light of the lieutenant's ignorance. Mr. Jenner. Put the lieutenant at a disadvantage? Mr. Thornley. Yes. Mr. Jenner. Were you present at any times when you were at El Toro when the lectures occurred when, at that time Oswald raised his hand and engaged in dissertation? Mr. Thornley. I might have been but I don't recall it if I was. I recall being present at several lectures at El Toro, and it just might have happened. It was the kind of thing Oswald would do and it wouldn't even have phased me. I probably wouldn't even have bothered to remember if it had happened. It would have been just part of the daily routine there so I would have—— Mr. Jenner. Did you ever engage in that sort of thing? Mr. Thornley. No; I never had guts enough to stand up and tell an officer he didn't know what he was talking about. Behind his back I might tell somebody that such-and-such officer didn't know what he was talking about, but I was never quite that brash—in that particular respect, anyway. Mr. Jenner. What were your impressions on Oswald being interested in music? Mr. Thornley. Not being interested in music myself particularly—— Mr. Jenner. I take it you had none; that is, any impressions as to his interests? Mr. Thornley. No, therefore, I had none; correct. Mr. Jenner. Did you ever play chess with him? Mr. Thornley. No. Mr. Jenner. Did you ever see him playing chess with anyone else?
Mr. Thornley. Just now you mentioned the word "chess" as a definite association; I think he did play chess. I can't place the person. This—there were some other people in the outfit who played chess. There is one name I have been trying to remember for a long time, and I think it starts with "Win" something. "Winter" something. I'm probably way off base there. But a tall blond corporal, I believe, played chess and a couple of other men in the outfit played chess. At that time, I guess at that, I knew how to play chess. I have never been particularly interested, though, in the game so I don't—I am pretty sure I didn't play chess with him. In fact, come to think of it I had just been cured of playing chess 3 months before that; somebody beat me in about six moves and I stopped playing for about a year. It wasn't me. Mr. Jenner. While at El Toro did Oswald become engaged in any physical altercations with anybody? Mr. Thornley. No; definitely not to my knowledge. Never got into any fights or even any hot personal argument over anything, that I know of. Mr. Jenner. What was your impression, if you had one then, as to his disposition in that regard? Mr. Thornley. I had the impression that he avoided violence. Mr. Jenner. While you were at El Toro do you recall whether Oswald ever went off the base on liberty? Mr. Thornley. As far as I know he didn't. Mr. Jenner. Were there any discussions on the base as to what, if anything, Oswald did? Mr. Thornley. Not in my presence. Mr. Jenner. What, if anything, Oswald had done off the base on liberty? Mr. Thornley. Not in my presence.
Mr. Jenner. Was there ever any discussion of Cuba and Castro and that problem? Mr. Thornley. Yes, sir. Mr. Jenner. All right; tell us all about that. Mr. Thornley. Well, at that time I and Oswald were both, and a couple of other men in the outfit, were quite sure that Castro was a great hero. Mr. Jenner. Why? Mr. Thornley. Well, he was liberating Cuba from Batista and, of course, we had heard all about Batista and what an evil man he was, which I am sure was true, and most of us had read some of the things written by Castro, some of Castro's promises—such as he would take no part in the government after the revolution, such things—so we had the definite impression—I remember there was one Puerto Rican boy, myself, Oswald, a couple of others who had quite an admiration for Castro, and thought the pro-Communist statements he was or might be making at the time, were made simply to guarantee a little more independence for his island because it was located so close to the United States. In other words, I felt at the time he was playing both ends against the middle in order to go his own way, something like Charles de Gaulle is doing right now by recognizing Red China. I felt it was purely statesmanship, statecraft, power politics. I didn't feel that Castro was a dedicated Communist. Whether Oswald did or not I don't know. He admired Castro because of the social reforms Castro was introducing. So did I at that time. Delgado, the Puerto Rican boy, as I recall it, was becoming worried at that time because he was beginning to think maybe Castro was communistic. I didn't think so. Oswald, as far as I know, didn't have anything to say on that matter. And that is about all I can tell you.
Mr. Jenner. Well, you say that you admired Castro and you knew Oswald admired Castro. Tell us on what you base that comment. Mr. Thornley. Well, once again as I remember, there was one of these afternoon discussions once again, and somebody was saying something, worried about Castro, it might have been Delgado, it might have been somebody else, I don't think it was Delgado that day because I think he was defending Castro, somebody said something against Castro, and Oswald said that he didn't think Castro was so bad. He thought Castro was good for Cuba, and they said why, and I took up the argument, which was the argument I just gave you, the naive idea I had at the time that he was playing for independence, and Oswald remained silent, shaking his head affirmatively a couple of times, and that was it. Mr. Jenner. Shaking his head affirmatively with respect to the comments you were making? Mr. Thornley. Yes; to my argument, to my justification of Castro. Mr. Jenner. But you recall no provocative remarks that he made in that connection? Mr. Thornley. No. Mr. Jenner. Did Oswald have a nickname? Mr. Thornley. Not that I know of except Oz sometimes. Mr. Jenner. Did you ever hear him referred to as "Ozzie Rabbit"? Mr. Thornley. Well, yes; I didn't realize that anybody else referred to him as such but I always thought of him as such. He reminded me very much of a cartoon character at that time. It was kind of pathetic. There was something about this little smile of his, and his expression on his face and the shape of his head, just the general, his general appearance established a definite association in my mind with some Warner Bros. cartoon character, I believe Warner Bros. And I, very recently, in a discussion with someone, describing
Oswald mentioned that he reminded you of—I said: "I think there is a character called Oswald Rabbit who appears in movie cartoons." And they shook their head. Now, I know where I got that particular example so I probably heard him referred to as "Ozzie Rabbit," though I don't recall specifically. Mr. Jenner. Did he occasionally have a nickname or a reference made to him attendant upon his interest in the study of the Russian language or his interest in communism or in Russia or Soviet—— Mr. Thornley. Only he was sometimes called the Communist and he would, sometimes I know—as far as his study of the Russian language went he made no attempt to hide this. In fact, he made—would make attempts to show it off by speaking a little Russian. Mr. Jenner. He was proud of that, was he? Mr. Thornley. Yes; there was someone else in the outfit who spoke Russian, don't ask me who, they used to exchange a few comments in the morning at muster and say hello to each other or something, and he also would make jokes in Russian, not in Russian, but in English, in a thick Russian accent many times; this was very typical of him. Mr. Jenner. He resorted to that area and use of satire? Mr. Thornley. Yes; until I had made the comment that implied he was a Communist, I had no idea—— Mr. Jenner. That he was sensitive? Mr. Thornley. That he was sensitive about it because he didn't seem to be. Mr. Jenner. Did he have any visitors? Mr. Thornley. Not that I recall.
Mr. Jenner. Was there any discussion at anytime about the possibility of his going to Russia? Mr. Thornley. No. Mr. Jenner. This was a complete surprise to you when you saw it in Stars and Stripes? Mr. Thornley. Somebody would say to him, "Why don't you go and live in Russia," in the middle of an argument. Mr. Jenner. I didn't mean that in that sense but did he volunteer a statement on his part about his going to Russia? Mr. Thornley. Never anything; no. Mr. Jenner. I take it it was your opinion he was not a Communist at the time he was assigned to El Toro? Mr. Thornley. That was my opinion. Mr. Jenner. I take it you have never seen or talked with Oswald subsequent to the time he left or you left for Japan, from El Toro? Mr. Thornley. No. Mr. Jenner. That is, my statement is correct. Mr. Thornley. Yes, sir. Mr. Jenner. It follows, I take it, that you were never aware that he was in New Orleans when you were there? Mr. Thornley. No; I wasn't. Mr. Jenner. You were not aware of his comings and goings other than the newspaper report that your folks sent you? Mr. Thornley. I was aware that he had come back from the Soviet Union and gone to Dallas, and I know I at that time did think about going to see him in Dallas for the book, to find out just why he did go to Russia, to check it with my own theory. Mr. Jenner. I am going to get to that in due course.
Mr. Thornley. But aside from knowing that he came back and went to live in Dallas with a Russian wife and a child I had no idea of his comings or goings. Mr. Jenner. At the time you had some notion of going to Dallas to see him or Fort Worth, as the case might be, it was with respect to the book you have talked about you were then in the process of writing or fulminating about? Mr. Thornley. Yes; it was practically—well, it was finished by that time but I was thinking about, I was definitely planning to rewrite it. I didn't know how soon, and I thought before I did rewrite it I would go talk to him and see what he could tell me about. There were a lot of gaps in the book, and in the book I was not able to explain how he got from the United States to Russia and things like that. A lot of things I wanted to check out and I thought if I could get him to cooperate with me, perhaps not even in telling him I was writing the book, I could get the information I wanted. Mr. Jenner. And this was the state of mind you had after you had heard that he returned to the United States? Mr. Thornley. Right. Mr. Jenner. Which was June of 1962, when he returned? Mr. Thornley. Right, and I had finished the book in February. Mr. Jenner. Of 1963? Mr. Thornley. 1962. Mr. Jenner. 1962. You were in Mexico and Mexico City in 1963? Mr. Thornley. Yes. Mr. Jenner. Cover that for us. What was the motivation, the length of the trip? Mr. Thornley. I will have to begin at the beginning on that. On April 17, my parents sent me a gift of $100 on the condition that I spend it for a bus ticket to visit them that summer. Which I did, and
I left around—well, I arrived in California on May 5. I remember going along the border and seeing fireworks on the other side of the border. Mr. Jenner. What border? Mr. Thornley. From Yuma to San Diego. Mr. Jenner. Mexican border? Mr. Thornley. That is Cinco De Mayo. I arrived in California on May 5 and I stayed there until late August. Now, I think in one of these reports that I gave to the FBI the information might be different. Since then I have checked with notebooks that I kept of my activity, and I was on my way back to New Orleans in late August. I went by way of Mexico City because I have taken 5 years of Spanish in school and I never had the opportunity to live in an environment where I would have to use it, depend on it solely, and I wanted to see how I would do. I have always wanted to visit Mexico, to see Mexico City. I checked into the prices. I had found out I had enough money that I would be able to go down to Mexico City and stay a short while. So I went down there for about a week, actually it was 6 days I spent within Mexico, from Tijuana to Mexico City, on a Mexican bus, and then when my money began to run out from Mexico City to Matamoros or Brownsville, Tex., on a Mexican bus. At this time, on my way up on a bus to Matamoros, it was September 2, because I had that in my notes, I have some notes about the bus ride and the date September 2. And I went from Brownsville to New Orleans by way of either Greyhound or Continental. Mr. Jenner. When did you arrive in New Orleans? Mr. Thornley. I went directly to New Orleans, so I imagine I arrived in New Orleans on September 3, possibly September 4.
Mr. Jenner. So that between approximately May 1, 1963, and September 4 and 5—— Mr. Thornley. Say May 3 to September 4. Mr. Jenner. You were not in New Orleans? Mr. Thornley. Right. Mr. Jenner. You were returning to your home in California? You stayed there for approximately a month or so? Mr. Thornley. Longer than that. Mr. Jenner. Longer than that. You then went to Mexico, Mexico City, and you then returned directly to New Orleans? Mr. Thornley. Yes, sir. Mr. Jenner. During none of that period of time did you have any contact with or hear anything about Oswald? Mr. Thornley. Definitely not. Mr. Jenner. You at one time at least were acquainted with a lady by the name of Sylvia Bortin? Mr. Thornley. Sylvia Bortin? Mr. Jenner. B-o-r-t-i-n. Mr. Thornley. Yes; this young lady, by the way—— Mr. Jenner. Where did she reside? Mr. Thornley. In Whittier, Calif., or at least last summer she did, I don't know where she resides now. This young lady, by the way, was mentioned in—her mention in this whole matter came out of a misunderstanding on my part of a question asked by the FBI agents. Mr. Jenner. All right. Would you explain that, please? Mr. Thornley. I don't recall what the question was—oh, yes, he had asked me something about, I believe it was the First Unitarian Church in Los Angeles. I had mentioned earlier at the time I was
talking to Oswald, and knew Oswald, I had been going to the First Unitarian Church in Los Angeles. This is a group of quite far to the left people politically for the most part, and mentioned in order to explain my political relationship with Oswald, at that moment, and he began to ask me questions about the First Unitarian Church and I answered, and then he realized or understood or asked what Oswald's connection with the First Unitarian Church was and I explained to him that there was none. Miss Bortin never knew Oswald and vice versa, and these people were two different parts of my life. There was this civilian compartment and the military compartment, and I never intermingled them. Mr. Jenner. This young lady married and her husband is now in Havana, Cuba? Mr. Thornley. That is what she told me last summer; yes. He was going to school in Cuba. Mr. Jenner. I take it this had nothing to do with yourself and Oswald's views with respect to Castro that you told us about. Mr. Thornley. No; this happened, I think, later, in fact I am sure it happened later. At that time Miss Bortin, she was then unmarried, did not know Robert Uname, I believe. I met him, I believe, September a year later. Mr. Jenner. Had you finished that? Mr. Thornley. Yes. Mr. Jenner. I take it that Oswald had no close personal friends at least that you observed? Mr. Thornley. That is correct. And the name of his closest friends I do not know. I do remember he had a close acquaintance that he seemed to get along with pretty well. Mr. Jenner. In the unit? Mr. Thornley. Yes; but I don't recall this man's name. If it was mentioned to me, I probably could, but——
Mr. Jenner. You were groping for it when you were interviewed. You suggested it might be Charles—— Mr. Thornley. I mentioned a Charles. Mr. Jenner. Weis. Mr. Thornley. Weir, but that was not the man. This was a friend of a friend of the friend or a man who could give them that information perhaps that I couldn't. At this time perhaps, also, I was thinking of a possibility it might have been Weir and since then I have remembered definitely who Weir was. Mr. Jenner. Who was he? Mr. Thornley. I don't remember whether his first name was Charles but I remember who he was. Mr. Jenner. He was a noncom? Mr. Thornley. There was a man named Cooley. There was somebody else, and these are my associations, but who it was who used to talk Russian in the ranks with Oswald in the morning I don't know, but that is who it was. Mr. Jenner. Is this particular man you now mentioned the man who occasionally talked Russian with Oswald in the ranks, is he the man who you had in mind? Mr. Thornley. Yes. Mr. Jenner. As having been a friend of Oswald's? Mr. Thornley. Yes; in that in the same respect that I was a friend of Oswald's. Once, again, the exact terminology I would use would be close acquaintance. Mr. Jenner. Yes; I would say from your description of the relationship with Oswald that it was more an acquaintanceship than a friendship.
Mr. Thornley. I think it was probably the same with this person from what I recall, to my knowledge. Mr. Jenner. In other words, when you say friend, he wasn't a buddy of Oswald? Mr. Thornley. No; Oswald was not the type of person who had, as it has been emphasized on all parts, I think, and it confirms my own impression, was not the type of person who made close friends or who stuck with close friends. Mr. Jenner. You saw no instance in which Oswald evidenced affection for anybody, I mean in the nice sense of the word? Mr. Thornley. No; none whatsoever. Mr. Jenner. Or anybody evidenced any affection in the nice sense of the word for him? Mr. Thornley. No. Mr. Jenner. I take it your trip to Mexico City was purely one of general interest as you have described and had nothing to do with any interest on your part in going to Cuba or attempting to go to Cuba? Mr. Thornley. Believe me, no. I have no desire to go to Cuba unless I am going to take a rifle and be on an invasion force or something. Mr. Jenner. Did you hear of anybody in the Marine Corps, whose last name was Hidell? Mr. Thornley. At the time this name was mentioned to me that was—that person, whoever it was that Oswald used to speak to in the ranks in the morning came to my mind. But I can't say that that was the name, and I am—of course, now, I am very leery that that —very uncertain as to ever having heard the name Hidell, and I doubt it very much. Mr. Jenner. Shortly after the unfortunate occurrence of November 22, 1963, you were interviewed by Secret Service agents, were you
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Entity Framework Tutorial Joydip Kanjilal

  • 1.
    Entity Framework TutorialJoydip Kanjilal download https://ebookbell.com/product/entity-framework-tutorial-joydip- kanjilal-4633638 Explore and download more ebooks at ebookbell.com
  • 2.
    Here are somerecommended products that we believe you will be interested in. You can click the link to download. Entity Framework Core In Action Second Edition Jon P Smith https://ebookbell.com/product/entity-framework-core-in-action-second- edition-jon-p-smith-57414396 Entity Framework 40 Recipes A Problemsolution Approach Larry Tenny https://ebookbell.com/product/entity-framework-40-recipes-a- problemsolution-approach-larry-tenny-2310094 Entity Framework 4 In Action Pappsc Stefano Mostarda Marco De Sanctis https://ebookbell.com/product/entity-framework-4-in-action-pappsc- stefano-mostarda-marco-de-sanctis-2321734 Entity Framework 41 Experts Cookbook Devlin Liles Tim Rayburn https://ebookbell.com/product/entity-framework-41-experts-cookbook- devlin-liles-tim-rayburn-2614594
  • 3.
    Entity Framework 6Recipes 2nd Edition Brian Driscoll Nitin Gupta https://ebookbell.com/product/entity-framework-6-recipes-2nd-edition- brian-driscoll-nitin-gupta-4569854 Entity Framework Core Cookbook 2nd Edition Ricardo Peres https://ebookbell.com/product/entity-framework-core-cookbook-2nd- edition-ricardo-peres-5853398 Entity Framework Core In Action 1st Edition Jon Smith https://ebookbell.com/product/entity-framework-core-in-action-1st- edition-jon-smith-7144114 Entity Framework 6 Recipes Second Edition Driscoll Briangupta https://ebookbell.com/product/entity-framework-6-recipes-second- edition-driscoll-briangupta-11810994 Entity Framework Core Kenji Elzerman https://ebookbell.com/product/entity-framework-core-kenji- elzerman-59128464
  • 6.
    Entity Framework Tutorial Learnto build a better data access layer with the ADO.NET Entity Framework and ADO.NET Data Services Joydip Kanjilal BIRMINGHAM - MUMBAI
  • 7.
    Entity Framework Tutorial Copyright© 2008 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, Packt Publishing, nor its dealers or distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: October 2008 Production Reference: 1201008 Published by Packt Publishing Ltd. 32 Lincoln Road Olton Birmingham, B27 6PA, UK. ISBN 978-1-847195-22-7 www.packtpub.com Cover Image by Vinayak Chittar (vinayak.chittar@gmail.com) [FM-2]
  • 8.
    Credits Author Joydip Kanjilal Reviewers Bogdan Brinzarea-Iamandi StefanTuralski Senior Acquisition Editor Douglas Paterson Development Editor Ved Prakash Jha Technical Editor Ajay Shanker Editorial Team Leader Mithil Kulkarni Project Manager Abhijeet Deobhakta Project Coordinator Lata Basantani Indexer Monica Ajmera Proofreader Joel T. Johnson Production Coordinator Aparna Bhagat Cover Work Aparna Bhagat [FM-3]
  • 9.
    About the Author JoydipKanjilal is a Microsoft MVP in ASP.NET. He has over 12 years of industry experience in IT with more than 6 years in Microsoft .NET and its related technologies. He has authored many articles for some of the most reputable sites like, www.asptoday.com, www.devx.com, www.aspalliance.com, www.aspnetpro.com, www.sql-server-performance.com, www.sswug.com, etc. Several of these articles have been featured at www.asp.net—Microsoft's Official Site on ASP.NET. Joydip was also a community credit winner at www.community-credit.com a number of times. He is currently working as a Senior Consultant in a reputable company in Hyderabad, INDIA. He has years of experience in designing and architecting solutions for various domains. His technical strengths include C, C++, VC++, Java, C#, Microsoft .NET, Ajax, Design Patterns, SQL Server, Operating Systems, and Computer Architecture. Joydip blogs at http://aspadvice.com/blogs/joydip and spends most of his time reading books, blogs, and writing books and articles. His hobbies include watching cricket and soccer and playing chess. Writing a book is always a rewarding experience. My special thanks to Douglas Paterson for providing me the opportunity to author this book—turning this idea into a reality. I am also thankful to the entire Packt team for their support. I am also thankful to Abhishek Kant (Microsoft), Steve Smith (AspAlliance), Russell Jones(DevX), Steve Jones(SSWUG), Jude Kelly (SQL Server Performance), and Anand Narayaswamy (AspAlliance) for their inspiration and support. My heartiest thanks to my friends Tilak and Vinod for their continued encouragement. My deepest respects and gratitude to my parents for their love, blessings, and encouragement. My thanks to my other family members too, for their support, and to little Jini in particular, for her continued inspiration and love. Thank you all so much! [FM-4]
  • 10.
    About the Reviewer BogdanBrinzarea-Iamandi has a strong background in Computer Science holding a Master and Bachelor Degree at the Automatic Control and Computers Faculty of the Politehnica University of Bucharest, Romania. He also holds an Auditor diploma at the Computer Science department at Ecole Polytechnique, Paris, France. His main interests cover a wide area from embedded programming, distributed and mobile computing, and new web technologies. Currently, he is employed as Supervisor within the team of Alternative Channels Sector of the IT Division in Banca Romaneasca, a Member of the National Bank of Greece. He is Project Manager for Internet Banking and he coordinates other projects related to new technologies and applications to be implemented within the banking area. Bogdan is also the author of two AJAX books, the popular AJAX and PHP: Building Responsive Web Applications and Microsoft AJAX Library Essentials, also by Packt. [FM-5]
  • 12.
    Table of Contents Preface1 Chapter 1: Introducing the ADO.NET Entity Framework 7 What You should Know 8 Looking Back 8 What is ADO.NET Entity Framework? 9 Is It Just Another ORM? 9 The ADO.NET Entity Framework Architectural Components 10 The Entity Data Model (EDM) 10 How is the Entity Data Model Represented? 13 The Object Model (O-Space) 15 LINQ to Entities 15 Entity Client 16 Entity SQL 16 Avoiding Complex Joins 17 The Object Services Layer 18 ADO.NET Entity Framework—Features and Benefits at a Glance 19 Installing the Prerequisites 20 Installing the ADO.NET Entity Framework and Its Tools 20 Downloading the Software 20 Installing the Software 21 Designing the Payroll Database 29 Summary 35 Glossary 35 Chapter 2: Getting Started 37 Creating an Entity Data Model 37 Creating the Payroll Entity Data Model Using the ADO.NET Entity Data Model Designer 38 Creating the Payroll Data Model Using the EdmGen Tool 47 The ADO.NET Entity Data Source Control 51
  • 13.
    Table of Contents [ii ] Implementing Our First Application Using the Entity Framework 54 Summary 57 Chapter 3: Entities, Relationships, and the Entity Data Model 59 Entities, Entity Types, and Relationships in the ADO.NET Entity Data Model (EDM) 59 What is an Entity? 60 Defining Entity Sets in the Entity Data Model 60 Extending the Existing Entity Types to Create Derived Entity Types 61 Association Sets, Associations, Containment, and Multiplicity 62 What are Entity Containers? 63 Exploring the Payroll Entity Data Model 64 The Mapping Details Window 65 The Entity Model Browser 67 The Entity Data Model Layers 68 The CSDL Schema 69 The SSDL Schema 75 The MSL Schema 80 Summary 84 Chapter 4: Working with Stored Procedures in the Entity Data Model 85 Mapping Stored Procedures to Functions in the EDM 85 Mapping Create, Update, and Delete Functions to Entities in the EDM 89 Mapping the Association Sets Consistently 93 Mapping Stored Procedures with No Entity Set 99 Using Stored Procedures 100 Mapping Stored Procedures that Return Custom Entity Types 101 Summary 102 Chapter 5: Working with Entity Client and Entity SQL 103 An Overview of the Entity SQL Language 104 From Transact SQL (T-SQL) to Entity SQL (E-SQL) 104 Why Entity SQL When I Already have LINQ to Entities? 105 Features of Entity SQL 105 Operators in Entity SQL 106 Arithmetic Operators 106 Comparison Operators 107 Logical Operators 107 Reference Operators 108 Type Operators 108 Set Operators 108 Operator Precedence 109 Expressions in Entity SQL 109 Query Expressions in Entity SQL 109
  • 14.
    Table of Contents [iii ] Identifiers, Variables, Parameters, and Types in Entity SQL 110 Row 111 Collection 111 Reference 112 Canonical Functions in Entity SQL 113 Mathematical Functions 113 Aggregate Functions 113 String Functions 114 Bitwise Functions 114 Date and Time Functions 115 Data Paging Using Entity SQL 115 Working with the ADO.NET Entity Client 116 Let's Get into Action 117 Building the Connection String 117 Creating an Entity Connection 118 Opening the Connection 118 Executing Queries Using the Entity Command 119 Closing the Connection 121 Other Operations with Entity SQL 123 Inserting a Record Using Entity SQL 123 Inserting a Record with a Foreign Key Constraint 124 Retrieving Native SQL from EntityCommand 124 Transaction Management in Entity SQL 125 Summary 126 Chapter 6: Working with LINQ to Entities 127 Introducing LINQ 127 Why LINQ? 128 Understanding the LINQ Architecture 128 LINQ to XML 129 LINQ to SQL 129 LINQ to Objects 130 LINQ to Entities 131 Querying Data Using LINQ to Entities 131 LINQ to Entities and Entity Framework 131 Differences between LINQ to Entities and LINQ to SQL 132 Operators in LINQ 133 Aggregation 136 Projections 136 Ordering 137 Quantifiers 137 Restriction 138 Conversion 138 Element 139 Set 139 Querying Data Using LINQ 140
  • 15.
    Table of Contents [iv ] Expressions in LINQ to Entities 143 Constant Expressions 144 Comparison Expressions 144 Initializing Expressions 145 Null Comparisons 146 Navigation Properties 147 Immediate and Deferred Query Execution 148 Improving Performance with Compiled Queries 150 Summary 150 Chapter 7: Working with the Object Services Layer 151 What are Object Services? 151 Features at a Glance 153 A Quick Look at the ObjectContext Class in our Payroll EDM 153 Querying Data as in-Memory Objects 156 Adding, Modifying, and Deleting Objects 156 Attaching and Detaching Objects to and from the Object Context 158 Serializing and De-Serializing Entity Instances 159 Change Tracking and Identity Resolution Using ObjectContext 161 Implementing a Sample Application 162 Creating the Form 162 Implementing a Custom DataContext 164 How is This Accomplished? 167 Inheritance in the Entity Framework 176 Table per Hierarchy 176 Table per Type 177 Implementing Complex Types in the EDM 180 Summary 181 Chapter 8: Introducing ADO.NET Data Services 183 Introducing ADO.NET Data Services 184 How Do ADO.NET Data Services and Web Services Differ? 184 What is Representational State Transfer (REST)? 184 Why Use ADO.NET Data Services? 185 Features at a Glance 185 Prerequisites 186 Exposing Data as a Service Using ADO.NET Data Services 186 Creating an ADO.NET Data Service 187 Using a Relational Database as the Data Source 189 Using Data Sources Other Than a Relational Database 192 Understanding the System.Services.Data Namespace 194 Restricting Access to Resources 196 Working with the ADO.NET Data Service Client Library 197 Generating the Client-Side Entity Classes 198
  • 16.
    Table of Contents [v ] Inserting a Record 198 Updating a Record 199 Deleting a Record 200 Consuming an ADO.NET Data Service Using LINQ 201 Exposing a Stored Procedure as a URI 201 Handling Exceptions in ADO.NET Data Services 202 Batching ADO.NET Data Services Requests to Improve Performance 204 Debugging Your Data Service 204 References 205 Summary 206 Index 207
  • 18.
    Preface The ADO.NET EntityFramework, the next generation of Microsoft's data access technology, is an extended Object Relational Mapping (ORM) technology that makes it easy to tie together the data in your database with the objects in your applications. This is done by abstracting the object model of an application from its relational or logical model. It is an extended ORM in the sense that it provides many additional features over an ORM. Some of these features are: Entity Inheritance and Composition Identity Resolution and Change Tracking LINQ Support The Object Service Layer This book is a clear and concise guide to the ADO.NET Entity Framework. Packed with plentiful code examples, this book helps you to learn the ADO.NET Entity Framework and ADO.NET Data Services and build a better data access layer for your application. What This Book Covers Chapter 1 is an introduction to the basics of the ADO.NET Entity Framework (EF), its usefulness, its features, and the benefits. Chapter 2 discusses how you can get started with EF, create an Entity Data Model (EDM), and write a program to query data. Chapter 3 gives a detailed explanation of entities, relationships, and each of the sections of the EDM. Chapter 4 provides a sample application that illustrates how to perform CRUD operations against the EDM. • • • •
  • 19.
    Preface [ 2 ] Chapter5 discusses the Entity SQL query language and how to work with the Entity Client provider. Chapter 6 includes a detailed discussion on LINQ to Entities with many code examples. Chapter 7 provides a detailed discussion on the Object Services Layer and its helpful and useful features. Chapter 8 provides an introduction to ADO.NET Data Services and how it can be used with the EDM to perform CRUD operations. What You Need for This Book To learn the concepts covered in this book, the reader should have a proper understanding and working knowledge of the following: ADO.NET ASP.NET C# To execute the code samples in this book, the following technologies should be installed in your system: Visual Studio 2008 Visual Studio 2008 SP1 SQL Server 2005 Windows XP/Vista/2003 or higher Who This Book is For This book is for C# developers who want an easier way to create their data access layer. You will need to be comfortable with ADO.NET, but you do not need to know anything about the Entity Framework. Along the way we will create some ASP.NET applications, so familiarity with this will be helpful. • • • • • • •
  • 20.
    Preface [ 3 ] Conventions Inthis book, you will find various styles of text that help distinguish between different kinds of information. Let's look at some examples of these styles, and an explanation of their meaning. Code words in text are shown as follows: "We can include other contexts through the use of the include directive." A block of code will be set as follows: <asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName" /> <asp:BoundField DataField="LastName" HeaderText="Last Name" SortExpression="LastName" /> When we wish to draw your attention to a particular part of a code block, the relevant lines or items will be made bold. Note that last two lines of the following code sample: <FunctionImport Name="DeleteEmployee"> <Parameter Name="EmployeeID" Mode="In" Type="Int32" /> <Parameter Name="DepartmentID" Mode="In" Type="Int32" /> <Parameter Name="DesignationID" Mode="In" Type="Int32" /> Any command-line input and output will be written as follows: edmgen /mode:fullgeneration /c:"Data Source=.;Initial Catalog=Payroll;User ID=sa;Password=joydip1@3;" /p:Payroll New terms and important words are introduced in a bold-type font. Words that you see on the screen, in menus or dialog boxes for example, appear in our text like this: "clicking the Next button moves you to the next screen". Important notes appear in a box like this with the Notes icon on the left.. Tips and tricks appear like this with the Tips icon on the left.
  • 21.
    Preface [ 4 ] ReaderFeedback Feedback from our readers is always welcome. Let us know what you think about this book, what you liked or may have disliked. Reader feedback is important for us to develop titles that you really get the most out of. To send us general feedback, simply drop an email to feedback@packtpub.com, making sure to mention the book title in the subject line of your message. If there is a book that you need and would like to see us publish, please send us a note in the SUGGEST A TITLE form on www.packtpub.com or email suggest@packtpub.com. If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide on www.packtpub.com/authors. Customer Support Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase. Downloading the Example Code for the Book Visit http://www.packtpub.com/files/code/5227_Code.zip to directly download the example code. The downloadable files contain instructions on how to use them. Errors Although we have taken every care to ensure the accuracy of our contents, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in text or code—we would be grateful if you would report this to us. By doing this you can save other readers from frustration, and help to improve subsequent versions of this book. If you find any errors, report them by visiting http://www.packtpub. com/support, selecting your book, clicking on the let us know link, and entering the details of your errors. Once your errors are verified, your submission will be accepted and the errata added to the list of existing errors. The existing errors can be viewed by selecting your title from http://www.packtpub.com/support.
  • 22.
    Preface [ 5 ] Piracy Piracyof copyright material on the Internet is an ongoing problem across all media. At Packt, we take the protection of our copyright and licenses very seriously. If you come across any illegal copies of our works in any form on the Internet, please provide the location address or website name immediately so we can pursue a remedy. Please contact us at copyright@packtpub.com with a link to the suspected pirated material. We appreciate your help in protecting our authors, and our ability to bring you valuable content. Questions You can contact us at questions@packtpub.com if you have a problem or question with some aspect of this book. We will do our best to address these questions and problems.
  • 24.
    Introducing the ADO.NET EntityFramework The ADO.NET Entity Framework is an extended Object Relational Mapping (ORM) technology from Microsoft that abstracts the object model of an application from its relational or logical model. That is, it isolates the object model from the way the data is actually represented in the relational store. This framework makes the conceptual model real by using an extended entity relationship model called the ADO.NET Entity Data Model. This chapter gives you an introduction to the ADO.NET Entity Framework and also equips you with a brief understanding of the related terminologies. We will revisit each of the Entity Framework architectural components as we progress through this book. Our journey of the ADO.NET Entity Framework has just begun! In this chapter, we will cover the following points: An overview of the ADO.NET Entity Framework The ADO.NET Entity Framework Architectural Components Features and benefits of the ADO.NET Entity Framework Installing the ADO.NET Entity Framework But, before we delve deep into this amazing technology from Microsoft, let's take a quick look at the prerequisites for learning the concepts covered in this book. • • • •
  • 25.
    Introducing the ADO.NETEntity Framework [ 8 ] What You should Know To learn the concepts covered in this book, the reader should have a basic understanding of the following: Programming using ADO.NET C# Working with ASP.NET Web Applications SQL Server Looking Back Any application has two perspectives. They are the Data Model and the Object Model. While the Data Model defines the way the data is defined and stored, the Object Model defines how the same data will be represented to the user in the presentation layer or, is exposed to the other layers of the application. The Data Model of the application usually deals with the storage and retrieval of the application's data to and from the relational store. The relational store is used for data persistence, consistency, concurrency, and security. It contains the application's data and typically comprises of a set of tables, views, functions, procedures, and the relationships. You typically use T-SQL to query against the relational store which returns result sets that contains columns and rows of data. However, the data returned doesn't necessarily match with the application's object oriented programming model. Usually, we don't use the data returned in the same form in which it is returned from the relational store. We write the necessary code to transform the data returned from the relational store to business objects in the data access layer of the application. Similarly, you need into write code to transform your application's business objects into a form that can be persisted into your relational store. But, what if the schema of the underlying relational store changes? To bridge this apparent mismatch between the data and the object models, ORM tools have evolved. They are used to reduce the code required to transform your application's business objects into a form that can be persisted into the relational store and vice-versa. • • • •
  • 26.
    Chapter 1 [ 9] What is ADO.NET Entity Framework? The ADO.NET Entity Framework is a type of ORM. It is a development platform that provides a layer of abstraction on top of the relational or logical model. In doing so, it isolates the object model of the application from the way the data is actually stored in the relational store. Developers can use the ADO.NET Entity Framework to program against an object model rather than the logical or relationship model. This level of abstraction is achieved using the Entity Data Model (EDM)—an extended Entity Relationship Model. The EDM reduces the dependency of your domain object model on the database schema of the data store in use. We will discuss more on this topic later in this chapter. Developers can use the ADO.NET Entity Framework to work with domain specific properties such as employee name employee address, contact details, etc, without having to be concerned with how the actual data is stored and represented in the underlying data store. The framework can take care of the necessary translations to either retrieve data from your data store, or, perform inserts, updates, and deletes. Is It Just Another ORM? The ADO.NET Entity Framework is an extended ORM technology from Microsoft. We say it is an extended ORM because it has many additional features compared to a typical ORM. ORMs often use metadata and factory classes to retrieve data or collections of data. On the contrary, using the Entity Framework, you can easily map your data to be accessible in a relational representation in the database to objects, no matter how the mapping is implemented. You can expose different data views to your application without having to change your relational schema. In essence, this allows the applications to have their own view of the data. The applications can even reuse the same views of data amongst themselves. The major difference between the ADO.NET Entity Framework and ORM tools is in the Entity Data Model and the former's ability to query data using strongly typed LINQ. You can even use Entity SQL, a T-SQL like query language for querying the Entity Data Model, to execute dynamic queries. In addition to what a typical ORM framework provides, the ADO.NET Entity Framework provides and supports entity inheritance, entity composition, and a flexible, loosely coupled three tiered model consisting of the conceptual model, the mapping layer, and the storage model. The ADO.NET Entity Framework enables you to even extend the existing schema. In other words, you can extend the generated entity classes to create your own custom entity classes. You can define relationships of any kind such as one-to-one, one-to-many, and even many-to-many. So, isn't it a better ORM?
  • 27.
    Introducing the ADO.NETEntity Framework [ 10 ] The ADO.NET Entity Framework Architectural Components The ADO.NET Entity Framework is comprised of the following components: The Entity Data Model LINQ to Entities Entity Client Entity SQL The Object Services Layer The following figure illustrates the layers of the ADO.NET Entity Framework and how they are related to each other: LINQ to Entities Object Services Object Query Entity SQL Entity SQL The Conceptual Model Layer (Defined using .CSDL files) The Mapping Layer (Defined using .MSDL files) The Logical Model Layer (Defined using .SSDL files) Database We will now discuss each of the components of the Entity Framework technology stack in the following sections. The Entity Data Model (EDM) The Entity Data Model, an extended entity relationship model, is the core of the ADO.NET Entity Framework. You can generate an Entity Data Model using the EDMGen.exe command line tool, or, using the ADO.NET Entity Data Model designer—a new Visual Studio template. We will discuss how an Entity Data Model can be generated from a relational schema in the next chapter. • • • • •
  • 28.
    Chapter 1 [ 11] The following figure illustrates where exactly the Entity Data Model fits in: .NET Objects or collection of .NET Objects The ADO.NET Entity Data Model The Relational Data Store The Entity Data Model abstracts the logical or the relational schema and exposes the conceptual schema of the data using a three-layered approach. It is comprised of the following layers: The Conceptual Data Definition Language Layer (C-Space) The Mapping Schema Definition Language Layer (C-S Space) The Store Space Definition Language Layer (S-Space) The following figure illustrates the layers of the Entity Data Model: The ADO.NET Entity Data Model Layers The Conceptual or the C-Space (GSDL) Comprises of EntityContainer, EntitySets, AssociationSets, Association Types, EntityTypes, Relationships and Functions Queried using Entity SQL or ESQL (EntityConnection, EntityCommand, EntityDataReader) The Mapping Layer or the C-S Mapping Layer (MSL) The Logical or the S-Space (SSDL) Comprises of Tables, Stored Procedures, Views and Functions Queried using ADO.NET Data Providers (SQLConnection, SQLCommand, SQLDataReader, SQLDataAdapter, etc using T-SQL or, using PL-SQL) • • •
  • 29.
    Introducing the ADO.NETEntity Framework [ 12 ] The Conceptual Layer or the C-Space Layer is responsible for defining the entities and their relationships. It defines your business objects and their relationships in XML files. The C-Space is modeled using CSDL and is comprised of EntityContainer, EntitySets, AssociationSets, AssociationTypes, EntityTypes, and Functions. You can query this layer using Entity SQL or ESQL (EntityConnection, EntityCommand, and EntityDataReader). The C-S Mapping Layer is responsible for mapping the conceptual and the logical layers. That is, it maps the business objects and the relationships defined in the conceptual layer with the tables and relationships defined in the logical layer. It is a mapping system created in XML, which links or maps the Conceptual and the Logical layers. The C-S Mapping layer is modeled using MSL. The Logical or the Storage Layer (also called the S-Space) represents the schema of the underlying database. This is comprised of tables, stored procedures, view, and functions. It is modeled using SSDL and queried using ADO.NET Data Providers. Hence, we use SQLConnection, SQLCommand, SQLDataReader, and SQLDataAdapter using T-SQL or PL-SQL if our data store is a SQL database. Here is how a typical Entity Data Model looks:
  • 30.
    Chapter 1 [ 13] How is the Entity Data Model Represented? The Entity Data Model uses the following three types of XML files to represent the C-Space, C-S Space, and the S-Space respectively. .CSDL (Conceptual Schema Definition Language): This represents the C-S Space and is used to map the entity types used in the conceptual model. .MSL (Mapping Schema Language): This represents the C-S Space and is used to map the logical model to the conceptual model. .SSDL (Store Schema Definition Language): This represents the S-Space and is used to map the schema information of the logical layer. If you use the ADO.NET Entity Data Model Designer tool to generate your Entity Data Model, you will have one .edmx file that contains the CSDL, MSL, and SSDL sections bundled into one single file. At runtime, the .csdl, .msl, and .ssdl files are created in the application's output directory. These files store the metadata information as XML for each of the above layers. Here is what the CSDL section of your Entity Data Model looks like: <!-- CSDL content --> <edmx:ConceptualModels> <EntityContainer Name="PayrollEntities"> <EntitySet Name="Designation" EntityType="PayrollModel. Designation" /> </EntityContainer> <EntityType Name="Designation"> <Key> <PropertyRef Name="DesignationID" /> </Key> <Property Name="DesignationID" Type="Int32" Nullable= "false" /> <Property Name="DesignationName" Type="String" Nullable="false" MaxLength="50" Unicode="false" /> <NavigationProperty Name="Employee" Relationship= "PayrollModel.FK_Employee_Designation" FromRole="Designation" ToRole="Employee" /> </EntityType> </edmx:ConceptualModels> • • •
  • 31.
    Introducing the ADO.NETEntity Framework [ 14 ] Here is how a typical SSDL section of the Entity Data Model looks like: <!-- SSDL content --> <edmx:StorageModels> <EntityContainer Name="dbo"> <EntitySet Name="Designation" EntityType= "PayrollModel.Store.Designation" /> </EntityContainer> <EntityType Name="Designation"> <Key> <PropertyRef Name="DesignationID" /> </Key> <Property Name="DesignationID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" /> <Property Name="DesignationName" Type="varchar" Nullable="false" MaxLength="50" /> </EntityType> </Schema> </edmx:StorageModels> And here is the C-S maping section for you: <!-- C-S mapping content --> <edmx:Mappings> <Mapping Space="C-S" xmlns="urn:schemas-microsoft-com:windows: storage:mapping:CS"> <EntityContainerMapping StorageEntityContainer="dbo" CdmEntityContainer="PayrollEntities"> <EntitySetMapping Name="Designation"> <EntityTypeMapping TypeName="IsTypeOf(PayrollModel. Designation)"> <MappingFragment StoreEntitySet="Designation"> <ScalarProperty Name="DesignationID" ColumnName= "DesignationID" /> <ScalarProperty Name="DesignationName" ColumnName= "DesignationName" /> </MappingFragment> </EntityTypeMapping> </EntitySetMapping> </EntityContainerMapping> </Mapping> </edmx:Mappings> </edmx:Runtime> </edmx:Edmx>
  • 32.
    Chapter 1 [ 15] You can also create abstract and complex types in your Entity Data Model. You can derive from an abstract type to create sub-types, but no instance of the abstract type can be created. You can also create complex types. That is, types that don't have any identity of their own. A typical example of a complex type is the Address type. We will skip further discussion on each of the sections of an Entity Data Model until Chapter 3. The Object Model (O-Space) When working with the ADO.NET Entity Framework, you will have an Object Model on top of all the Entity Data Model layers. You need to model the Object Model using .NET objects. The following figure illustrates how the Object Model fits in with the EDM layers: The Object Model or the O-Space The O-C Mapping Layer The Conceptual Model or the C-Space (Modelled using CSDL) The Mapping Layer or the C-S Space (Modelled using MSL) The Logical Model or the S-Space (Modelled using SSDL) The Object Model Layer contains, .NET objects, collection of .NET objects, types, properties and methods. You can use the Object Model or the O-Space Model to query your business objects, or the collections of your business objects, using LINQ to Entities or Entity SQL. The C-Space and O-Space models are actually mapped by the O-C Mapping Layer using code attributes applied to the O-space Model. LINQ to Entities Language Integrated Query (LINQ) is a query translation pipeline that has been introduced as part of the C# 3.0 library. It comprises a set of query operators for different data sources (LDAP, Objects, CSV, XML, Entities, SQL, etc.). It is an extension of the C# language and provides a simplified framework for accessing relational data in a strongly typed, Object Oriented manner.
  • 33.
    Introducing the ADO.NETEntity Framework [ 16 ] LINQ to Entities is a Microsoft technology that enables you to query your business objects from within the language in a strongly typed manner. You can use LINQ to Entities, a superset of LINQ to SQL, to query data against a conceptual data model, namely, the Entity Data Model. We will learn more on LINQ and LINQ to Entities in the chapter 6. Here is an example of a typical LINQ to Entities query: PayrollModel.PayrollEntities ctx = new PayrollModel.PayrollEntities(); var query = from emp in ctx.Employee select emp; foreach (var employee in query) Response.Write("<BR>"+employee.FirstName); LINQ to Entities rests on top of the ADO.NET Entity Framework's Object Services Layer and that the LINQ to Entities queries are internally translated to canonical query trees. This, in turn, gets converted internally to corresponding SQL queries in a form expected by your underlying database. Entity Client Entity Client, the gateway to entity-level queries, is the Entity Framework's counterpart of ADO.NET's SQL Client or Oracle Client that uses Entity SQL or E-SQL to query the conceptual model. You create a connection using Entity Connection, execute commands through Entity Commands, and retrieve the result sets as Entity Data Readers. Entity SQL Entity SQL is a data store independent derivative of T-SQL that supports entity inheritance and relationships. You can use it to query data using the conceptual schema. You can even build your own dynamic queries. These E-SQL queries are internally translated to data store dependent SQL queries. This translation, that is, the conversion of the E-SQL queries to their data store-specific query language like T-SQL, (it doesn't need to be only T-SQL, however, it is the supported one) is handled by the Entity Framework. Entity SQL or E-SQL may not be as strongly typed as LINQ is, but, you have the flexibility of executing dynamic queries using it, much like T-SQL.
  • 34.
    Chapter 1 [ 17] Strongly typed data access is one of the most striking features of LINQ. LINQ queries are checked at compile time. This is unlike SQL queries which are only detected at runtime. But, why do you need Entity SQL when you have LINQ to Entities to query data through you Entity Data Model? You can, using Entity SQL, compose queries that are difficult to determine until the time the query is executed. On a different note, Entity SQL is a full text-based query language that you can use in much the same way as you use ADO.NET data providers. Here is an example that shows how you can use Entity SQL to insert data in your applications. using (EntityConnection conn = new EntityConnection("Name=PayrollEnti ties")) { try { conn.Open(); EntityCommand cmd = conn.CreateCommand(); cmd.CommandText = "PayrollEntities.AddNewEmployee"; cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.AddWithValue("FirstName", "Joydip"); cmd.Parameters.AddWithValue("LastName", "Kanjilal"); cmd.Parameters.AddWithValue("Address", "Hyderabad"); cmd.Parameters.AddWithValue("DepartmentID", 4); cmd.ExecuteNonQuery(); } catch (Exception ex) { Response.Write(ex.ToString()); } } To query data from the Entity Data Model, you have three choices—Entity SQL, LINQ to Entities, and Object Services. Avoiding Complex Joins You can use Entity SQL to avoid complex joins as you will typically be querying against a conceptual model of the data. As an example, if we want to display employee names and the department names in which they work, we would have to join the information of the Employee and the Department tables and then filter the unwanted columns to retrieve only the information that is required. Such traversals become a nightmare as you add additional tables and you therefore require more complex joins.
  • 35.
    Introducing the ADO.NETEntity Framework [ 18 ] When you implement your Object Model using Object Oriented Programming Languages, you expose the object's relationships with other objects of its kind using properties. This is in contrast to the approach we just discussed. Hence, designing an Object Model using this approach is cumbersome. This is exactly where the ADO. NET Entity Framework fits in; it represents the conceptual and logical model of data while using grammar that is common to both. Here is a code snippet that explains how you can use Entity SQL to avoid complex joins in your application's code. The following T-SQL query can be used to retrieve employee data split across three tables, namely, Employee, Department, and Salary. Select Employee.FirstName, Employee.LastName, Department. DepartmentName, Salary.Basic from Employee INNER JOIN Department on Department.DepartmentID = Employee.DepartmentID INNER JOIN Salary on Salary.EmployeeID = Employee.EmployeeID And, here is how you will use the Entity SQL to achieve the same result: Select FirstName, LastName, DepartmentName, Basic from EmployeeData The Object Services Layer Apart from querying the Conceptual Model, you might, at some point, have to work with entities such as in-memory objects or a collection of in-memory objects. To do this you need Object Services. You can use it to query data, from almost any data store, with less code. In addition to from enabling you to perform CRUD operations, the Object Services Layer provides the following additional services: Change tracking Lazy loading Inheritance Optimistic concurrency Merging data Identity resolution Support for querying data using Entity SQL and LINQ to Entities We will learn more about Object Services later in the book. The Object Services Layer internally uses an Object Query object for query processing. Note that the Object Services Layer supports querying data using both Entity SQL and LINQ to Entities. • • • • • • •
  • 36.
    Chapter 1 [ 19] You can query data from the Entity Data Model either using Object Services or Entity Client. However, if you require change tracking, be aware that only Object Services provides this feature. Note that in either case, the ADO.NET Data Providers are responsible for talking to the underlying database. Here is an example that shows how you can use Object Services to retrieve data. using (ObjectContext ctx = new ObjectContext("Name=PayrollEntities")) { var query = from employee in ctx.CreateQuery<PayrollModel. Employee>("PayrollEntities. Employee") select employee; foreach (PayrollModel.Employee emp in query) { Response.Write("<BR>" + emp.FirstName); } } ADO.NET Entity Framework—Features and Benefits at a Glance Here is a quick look at some of the features and benefits of the ADO.NET Entity Framework: Increased level of abstraction. An extensible and flexible provider model. Seamless querying of data using Entity SQL and LINQ. A flexible schema for storing the mapping information. Reduction to the amount of KLOC needed to write data access code in your applications. Provides a layer of abstraction on top of any data store as long as an implementation for the underlying data store is provided. A powerful Object Services Layer. A full text-based query language. Support for a conceptual data model of an application. • • • • • • • • •
  • 37.
    Introducing the ADO.NETEntity Framework [ 20 ] KLOC refers to Kilo Lines of Code, a unit of measuring the amount of source code in your programs. Installing the Prerequisites To run the programs given in this book, you should have the following elements installed on your system: Visual Studio.NET 2008 Professional SQL Server 2005 or higher Microsoft .NET Framework 3.5 SP1 ADO.NET Entity Framework Beta 3 or higher ADO.NET Entity Framework Tools December 2007 CTP or higher Installing the ADO.NET Entity Framework and Its Tools Before you proceed with installing EF Beta 3 and its tools, make sure that you have installed Visual Studio.NET 2008 Professional and SQL Server 2005 on your system. I will skip the discussion on installing Visual Studio 2008 Professional and SQL Server 2005 at this time. Downloading the Software Let us take a look at the necessary software that you need to download in order to work with the ADO.NET Entity Framework. Download ADO.NET Entity Framework Beta 3 from the following link: http://www.microsoft.com/downloads/details. aspx?FamilyId=15DB9989-1621-444D-9B18-D1A04A21B519&displaylang =en Download ADO.NET Entity Framework Tools December 2007 CTP from the link give below: http://www.microsoft.com/downloads/details. aspx?FamilyId=D8AE4404-8E05-41FC-94C8-C73D9E238F82&displaylang =en • • • • • • •
  • 38.
    Chapter 1 [ 21] Download the patch update to Visual Studio.NET 2008 from the link given below: http://go.microsoft.com/fwlink/?LinkID=104985 Download Microsoft .NET Framework 3.5 SP1 from the following link: http://www.microsoft.com/downloads/details. aspx?FamilyId=8C36ACA4-E947-4760-9B05-93CAC04C6F87&displaylang =en Installing the Software Now that the required software has been downloaded, we will now install each one individually. Double-click on the ADO.NET Entity Framework Setup file. The following installation wizard window will appear: Now, click on Next. • •
  • 39.
    Introducing the ADO.NETEntity Framework [ 22 ] Here is how the next screen looks like: In the above window that appears, check the checkbox and click on Install. The installation procedure starts and when done, the following screen appears:
  • 40.
    Chapter 1 [ 23] Click on Finish to complete the installation process. Now that you have installed the ADO.NET Entity Framework successfully on your system, the next step is to install the ADO.NET Entity Framework Tools CTP. But before you do that, you need to install the Visual Studio.NET 2008 patch update. Double-click on the Visual Studio.NET patch update setup file that you downloaded earlier. The following window appears: Now, click on Next.
  • 41.
    Introducing the ADO.NETEntity Framework [ 24 ] The following window appears: Check the check box to agree and accept the license terms and click on Next to start the installation process. Once the installation is complete, the following window appears:
  • 42.
    Chapter 1 [ 25] Click on Finish to complete the installation process. Now, we need to install the ADO.NET Entity Framework Tools CTP. To do this, double-click on the ADO.NET Entity Framework December 2007 Tools CTP you downloaded earlier. The following screen appears:
  • 43.
    Introducing the ADO.NETEntity Framework [ 26 ] Click on Next. The following window appears: Now, check the check box to accept the license terms and click on Next. The following window will appear:
  • 44.
    Chapter 1 [ 27] Click on Install to start the installation process. Once the installation is complete, the following window is displayed: Clink on Finish to complete the installation process. We will now install Microsoft .NET Framework 3.5 SP1. It contains many additional features and most importantly, we need it to work with the Entity Data Source control. We will discuss this control in the next chapter.
  • 45.
    Introducing the ADO.NETEntity Framework [ 28 ] To install Microsoft .NET Framework 3.5 SP1 on your system, double-click on the setup file you downloaded earlier. The following screenshot shows the window that will appear: Select the radio button to accept the terms of the license agreement and click on Install to start the installation process.
  • 46.
    Chapter 1 [ 29] Once the installation process is complete, the following window is displayed: Click on Exit to complete the installation process. You are done! Having installed these prerequisites, we will now design our sample database. We will use this database throughout this book. We will assign the name Payroll to our design database. The next section discusses the design of this sample database. Designing the Payroll Database In this section, we will design our Payroll database, which we will use throughout this book. This database will comprised of the following five tables: Employee Department Designation Salary Provident Fund • • • • •
  • 47.
    Introducing the ADO.NETEntity Framework [ 30 ] Here is the script for creating these tables. CREATE TABLE [dbo].[Employee]( [EmployeeID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [LastName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [Address] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [Phone] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [DepartmentID] [int] NOT NULL, [JoiningDate] [datetime] NOT NULL, [LeavingDate] [datetime] NULL, [DesignationID] [int] NOT NULL, CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED ( [EmployeeID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Department]( [DepartmentID] [bigint] NOT NULL, [DepartmentName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [DepartmentHead] [bigint] NOT NULL, CONSTRAINT [PK_Department] PRIMARY KEY CLUSTERED ( [DepartmentID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Designation]( [DesignationID] [bigint] NOT NULL, [DesignationName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_ AS NOT NULL, CONSTRAINT [PK_Designation] PRIMARY KEY CLUSTERED ( [DesignationID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[Salary]( [SalaryID] [bigint] NOT NULL, [EmployeeID] [bigint] NOT NULL, [Basic] [money] NOT NULL, [Allowance] [money] NOT NULL, [PFID] [bigint] NULL, [Tax] [money] NOT NULL, [GrossSalary] [money] NOT NULL,
  • 48.
    Chapter 1 [ 31] [NetSalary] [money] NOT NULL, CONSTRAINT [PK_Salary] PRIMARY KEY CLUSTERED ( [SalaryID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] CREATE TABLE [dbo].[ProvidentFund]( [PFID] [bigint] NOT NULL, [PFAmount] [money] NOT NULL, CONSTRAINT [PK_ProvidentFund] PRIMARY KEY CLUSTERED ( [PFID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] Here is how the database diagram for our Payroll database looks:
  • 49.
    Introducing the ADO.NETEntity Framework [ 32 ] We will create some stored procedures now that we will use to insert, update, and delete data from the tables we just created. Here is a list of the stored procedures that we will create for our Payroll database: Employee_Insert Employee_Update Employee_Delete Department_Insert Department_Update Department_Delete Designation_Insert Designation_Update Designation_Delete ProvidentFund_Insert ProvidentFund_Update ProvidentFund_Delete Salary_Insert Salary_Update Salary_Delete Here is the script for these procedures. Create Procedure Employee_Insert As @FirstName varchar(50), @LastName varchar(50), @Address varchar(50), @Phone varchar(50), @DepartmentID int, @DesignationID int, @JoiningDate datetime, @LeavingDate datetime as Insert into Employee(DepartmentID, DesignationID, JoiningDate, LeavingDate) values (@DepartmentID, @DesignationID, @JoiningDate, @LeavingDate) Go Create Procedure Employee_Update @EmployeeID int, @FirstName varchar(50), @LastName varchar(50), @Address varchar(50), @Phone varchar(50), @DepartmentID int, @DesignationID int as Update Employee Set DepartmentID = @DepartmentID, DesignationID = @DesignationID Where Employee.EmployeeID = @EmployeeID • • • • • • • • • • • • • • •
  • 50.
    Chapter 1 [ 33] Go Create Procedure Employee_Delete @EmployeeID int as Delete from Employee where Employee.EmployeeID = @EmployeeID Go Create Procedure Department_Insert @DepartmentName varchar(50) as Insert into Department (DepartmentName) values (@DepartmentName) Go Create Procedure Department_Update @DepartmentID int,@DepartmentName varchar(50) as Update Department Set DepartmentName = @DepartmentName where DepartmentID = @DepartmentID Go Create Procedure Department_Delete @DepartmentID int as Delete from Department where DepartmentID = @DepartmentID Go Create Procedure Designation_Insert @DesignationName varchar(50) as Insert into Designation (DesignationName) values (@DesignationName) Go Create Procedure Designation_Update @DesignationID int, @DesignationName varchar(50) as Update Designation Set DesignationName = @DesignationName where DesignationID=@DesignationID Go Create Procedure Designation_Delete @DesignationID int as Delete from Designation where DesignationID=@DesignationID Go Create Procedure ProvidentFund_Insert @EmployeeID int, @PFAmount money as Insert into ProvidentFund (EmployeeID, PFAmount) values (@EmployeeID, @PFAmount)
  • 51.
    Introducing the ADO.NETEntity Framework [ 34 ] Go Create Procedure ProvidentFund_Update @PFID int, @EmployeeID int, @PFAmount money as Update ProvidentFund set EmployeeID = @EmployeeID, PFAmount = @PFAmount where PFID = @PFID Go Create Procedure ProvidentFund_Delete @PFID int as Delete from ProvidentFund where PFID = @PFID Go Create Procedure Salary_Insert @EmployeeID int, @PFID int, @Basic money, @Allowance money, @Tax money, @GrossSalary money, @NetSalary money as Insert into Salary(EmployeeID, PFID, Basic, Allowance, Tax, GrossSalary, NetSalary) values (@EmployeeID, @PFID, @Basic, @Allowance, @Tax, @GrossSalary, @NetSalary) Go Create Procedure Salary_Update @SalaryID int, @EmployeeID int, @PFID int, @Basic money, @Allowance money, @Tax money, @GrossSalary money, @NetSalary money as Update Salary set EmployeeID = @EmployeeID, PFID = @PFID, Basic = @Basic, Allowance = @Allowance, Tax = @Tax, GrossSalary = @ GrossSalary, NetSalary = @NetSalary where SalaryID = @SalaryID Go Create Procedure Salary_Delete @SalaryID int as Delete from Salary where SalaryID = @SalaryID We will add more tables and stored procedures to our Payroll database as necessary in the chapters to follow.
  • 52.
    Chapter 1 [ 35] Summary The ADO.NET Entity Framework mainly addressees how easily you can persist and query your data with many of added services. You can use the ADO.NET Entity Framework to focus on the object model rather than the logical model. In other words, you can add a level of abstraction on top of your relational store. In this chapter, we have had a look at what this framework is, its architecture, advantages, and how it differs from LINQ to SQL (formerly called DLINQ). In the next chapter, we will learn how to get started with the ADO.NET Entity Framework. Glossary Entity: This is the core concept in the Entity Framework. An Entity essentially models individual objects, like, employees, customers, etc. It is something that is uniquely definable, distinctly identifiable, and contains information pertaining to the entity. Relational or Logical Model: A relational or logical model depicts the logical view of data that comprises of the normalized entities and their inter-relationships in a database. Object Model: An Object Model may be defined as a collection of the objects, members, and properties of a class and the relationships between them that illustrates the structure of a system. An Object Model of a system is centered on the three basic properties of Object Oriented Programming—encapsulation, abstraction, and inheritance. The Entity Data Model (EDM) is an implementation for the Entity – Relationship model (commonly called the E-R model). It depicts the entities and their relationships. The EDM is a view of the data store that your application will use.
  • 54.
    Getting Started In theprevious chapter we took a look at the ADO.NET Entity Framework including its architecture and its features. We also designed our Payroll database that we will be using throughout this book to store and retrieve data. We will use the same database in this chapter to generate an Entity Data Model and then use it, along with the Entity Data Source control, to bind data to a GridView data control. In this chapter, we will cover the following points: Creating an Entity Data Model Introducing the Entity Data Source Control Implementing our first application using the ADO.NET Entity Framework We will start this chapter with a discussion on how we can create an Entity Data Model from our Payroll database. Creating an Entity Data Model You can create the ADO.NET Entity Data Model in one of two ways: Use the ADO.NET Entity Data Model Designer Use the command line Entity Data Model Designer called EdmGen.exe We will first take a look at how we can design an Entity Data Model using the ADO. NET Entity Data Model Designer which is a Visual Studio wizard that is enabled after you install ADO.NET Entity Framework and its tools. It provides a graphical interface that you can use to generate an Entity Data Model. • • • • •
  • 55.
    Another Random Documenton Scribd Without Any Related Topics
  • 56.
    about his family,anything along this line and I don't think I ever discussed my past with him. Mr. Jenner. Was any mention ever made of his attendance at or even the name of the Albert Schweitzer College? Mr. Thornley. No. Mr. Jenner. No discussions about any plans of his or possibility of his seeking further education of any kind or character when he was mustered out of the Marines? Mr. Thornley. None whatsoever. For one thing we were not close enough friends to have any personal interests in each other. I looked upon him as somebody to argue with, another atheist—therefore, without the problem of religion between us—and to argue philosophy and politics about, and I think he looked upon me in about the same light. Mr. Jenner. What was your dexterity with Marine weapons? Mr. Thornley. Mine? Mr. Jenner. Yes. Mr. Thornley. I was a sharpshooter. Mr. Jenner. What was his? Mr. Thornley. I believe—well, at that time I didn't know. Mr. Jenner. You didn't know. I want your viewpoint as of that time. While you were based at El Toro, did the unit engage with any regularity in rifle practice? Mr. Thornley. None whatsoever. At that time, the whole time I was there, we did not engage in rifle practice. Mr. Jenner. As a matter of curiosity on my own part, why was that? Mr. Thornley. Well, in the Marine Corps you are required once a year to go to the rifle range and qualify. I was not there an entire year. Point No. 2, this was the Marine air wing which has much less
  • 57.
    of an emphasison, in general, on rifle practice because it is not going to be utilized in battle, and a much stronger emphasis, in the case of the outfit we were in, on our particular military occupational specialty. Mr. Jenner. Which was? Mr. Thornley. 6749 Aviation Electronic Operator. Mr. Jenner. Was this true when you reached Japan? Mr. Thornley. More so. When I reached Japan, however, we did go to the rifle range one time shortly after I got there, and qualify. I recall at that time that in Japan we weren't even having rifle inspections. There you could put your rifle away in your locker and forget about it, and take it out every couple of months and make sure it hadn't corroded away, and put it back again. Mr. Jenner. But you didn't even have rifle inspection? Mr. Thornley. Once in a while we would have one, but not with any frequency whatsoever. Mr. Jenner. Were you forewarned so that you could clean your rifle? Mr. Thornley. No; usually you were caught unawares, which was why you kept it clean in the locker. Mr. Jenner. I see. What are the grades of marksmanship? Mr. Thornley. Marksman, sharpshooter, and expert. Mr. Jenner. Marksman, sharpshooter, and expert. Therefore, I gather from that that marksman was the basic grade. Mr. Thornley. Yes. Mr. Jenner. A grade that every marine was expected to, and had to, attain that grade? Mr. Thornley. Not had to attain, some didn't, and there was no particular penalty involved, except maybe something a little extracurricular when you were in boot camp. Otherwise, you didn't
  • 58.
    wear a marksman'smedal is all. You didn't have any qualification in the infantry; of course, it would be looked down upon in the case of promotion or something like that. In the air wing it had much slighter significance than that. Maybe if you were being considered for a meritorious promotion and you hadn't qualified you wouldn't get it, but day to day it had no significance. Mr. Jenner. Were the standards applied in the air wing with respect to qualifications for these three classes as severe or as high as the standards applied, let us say, in the Marine infantry? Mr. Thornley. Exactly the same; yes. Mr. Jenner. Exactly the same. Would you please state for me your concept of the degree of marksmanship for (a) marksman, (b) sharpshooter, (c) expert? Mr. Thornley. Well, a marksman is an average shooter. A man, I think, could pick up a rifle and with a little commonsense and a minimum knowledge of the basics of marksmanship qualify as a marksman. When a man doesn't qualify as a marksman it is usually either because he is nervous on the day of qualification or he is gun shy or some outside influence confuses him; maybe he gets his windage off, something like this. Sharpshooter is just a little above average. It ranges over about —a pretty wide field. But it is a man who—a sharpshooter would be a man, the average man, with a good, maybe a week of training on how to use a rifle, and some practice. Whereas an expert is the kind of man I would hate to have on the other side in a war. He is accurate with his rifle up to and including 500 yards in a number of different positions. Hits the bull's- eye or close to the bull's-eye an overwhelming percentage of the time. Mr. Jenner. Is that the category in which we would place that to which we refer generally as the sniper?
  • 59.
    Mr. Thornley. Yes.Well, any man might be assigned as a sniper, I imagine. But an expert rifleman would perform much better. Mr. Jenner. Maybe be a superior sniper. Mr. Thornley. Yes. Definitely. Mr. Jenner. And to attain the position of expert marksman must there be considerable practice and use of the weapon or is it more of natural ability? Mr. Thornley. Now, you enter in once again to natural ability, just as not qualifying might be caused by a lack of natural ability of some kind. An expert rifleman probably would have a much calmer nervous system or, you might say, a much greater degree of control. I would imagine training can make up for this. I know a couple of times I just missed expert by a few points. It seemed that I couldn't make expert. It seemed to me there was just something I didn't have in order to make expert. It was very frustrating. Mr. Jenner. You tried? Mr. Thornley. Yes; it takes a great degree of control, primarily. Of course, the other things like good eyesight and so on and so forth. Mr. Jenner. Oh, yes. Mr. Thornley. Yes. Mr. Jenner. Did you ever discuss with Oswald his degree of proficiency in the use of the rifle? Mr. Thornley. Not to the best of my knowledge. Mr. Jenner. Did you have any impressions that you gathered in that respect while you were with him at El Toro? Mr. Thornley. None whatsoever. Had somebody asked me to guess about Oswald, I would have said, well, he probably didn't qualify, just because that was the type of guy he was, but that is all. Mr. Jenner. You would never have expected him to have been a sharpshooter, for example?
  • 60.
    Mr. Thornley. Itwouldn't have greatly surprised me if he was and it wouldn't have greatly surprised me if he wasn't. This is something very difficult: to look at a man and tell, at least it is very difficult for me. I have seen some drill instructors who could do it. But to tell whether he is going to be an expert or a sharpshooter, marksman, I am not qualified. Mr. Jenner. While you were stationed with him at El Toro, did you ever go off base with him? Mr. Thornley. No. Mr. Jenner. Did you ever have any discussion of dates? Mr. Thornley. No. Mr. Jenner. His attitude toward women? Mr. Thornley. No. Mr. Jenner. Sex? Mr. Thornley. None whatsoever. Mr. Jenner. Was there any scuttlebutt around the camp in that regard with respect to him? Mr. Thornley. Not to the best of my knowledge. Mr. Jenner. Sex habits, propensities? Mr. Thornley. No; you stand a risk in the Marine Corps, if you are at all quiet and tend to be introverted, of being suspected of being homosexual, but to the best of my knowledge there were never any comments made of this nature. Mr. Jenner. Do you recall some other readings of his in addition to "1984"? Mr. Thornley. I do recall having mentioned Dostoievsky to him and I know he had read something and I think it was "Crime and Punishment" but I am not sure. It was something I had not read by Dostoievsky when I had read about, I guess at that time, about three or four books.
  • 61.
    Mr. Jenner. Itis a great book. Mr. Thornley. Someday I am going to get around to it. Mr. Jenner. Have you not read it yet? It is a really great book. Mr. Thornley. No; and I don't recall him mentioning any other books offhand. I don't—I can't think of a thing besides "1984" and some book by Dostoievsky. Mr. Jenner. While you were based at El Toro did he engage, did you notice, in any officer baiting on his part with respect, in particular, to such matters as foreign affairs? Mr. Thornley. Yes; not on foreign affairs, no, but the same officer, Lieutenant Donovan, spoke of in a foreign affairs lecture in the newspapers, I do remember him baiting him on a couple of occasions. Mr. Jenner. Oswald attempting to bait Lieutenant Donovan? Mr. Thornley. I don't remember what it was. I know, I believe Lieutenant Donovan was also a lieutenant which I had had a couple of run-ins with if I remember correctly. If not, it was Lieutenant Delprado. It was one of the two of them. Mine were completely accidental and I went to great length to keep away from one of them because it seemed like any time I was around him I happened to do something to irritate him. But Oswald, I don't recall exactly what he said, but he a couple or three times went out of his way to say something to one of these lieutenants that would cause them to be irritated and in this you can't really say that he was exceptional. It happened many times. In Oswald's case though, it was exceptionally—— Mr. Jenner. You mean it happened many times with respect to other noncoms in the Marines with respect to these officers? Mr. Thornley. Right; but in Oswald's case it seemed a little more deliberate. Some guys would get mad and they would say something, or sometimes they would do something by accident, and
  • 62.
    they would getthemselves involved and then they would decide, "Well, what the hell," and push it all away. Oswald it seemed didn't have to have any reason. He just told an officer to get lost. Mr. Jenner. He baited an officer for the pleasure of it? Mr. Thornley. Yes; I might mention that this was one means by which he won the admiration of others in the outfit in that the junior officers especially are usually disliked, or were in that outfit, and this made him on such occasions as he engaged with an officer in some kind of officer baiting, this won the respect, for at least a few minutes, of the men—who would kind of laugh about it, and chuckle over it and tell others about it. Perhaps this is why he did it. Mr. Jenner. You mentioned some slovenliness on his part; what about his quarters, his barracks; did you have occasion to observe them? Mr. Thornley. I don't think I was ever in his barracks. I do recall having been told that he had Russian books and that is all I—that is the only connection I can make now in my mind with his quarters. I don't think I ever saw them. Mr. Jenner. You already have given us something of his view of the U.S. Marine Corps. Would you give us a summary of that? Give us your impression of his views with respect to the U.S. Marine Corps. Mr. Thornley. Well, definitely the Marine Corps was not what he had expected it to be when he joined. Also he felt that the officers and the staff NCO's at the Marine Corps were incompetent to give him orders. Mr. Jenner. Incompetent in what sense, they were below him intellectually? Mr. Thornley. They were below him intellectually—and for various other reasons in each case, too. Maybe this officer was ignorant, as was brought out about foreign affairs, in Oswald's mind, knew less than Oswald did about it. I don't hold with the stand that Oswald
  • 63.
    would study upon foreign affairs simply in order to bait the officer. I think it just happened to be that Oswald would see that the officer was basing his foreign affairs maybe on Time magazine when Oswald had done a little more reading and I think he resented this Time magazine approach to foreign affairs. Mr. Jenner. How did these discussions arise, Mr. Thornley, the discussion of foreign affairs by officers? Mr. Thornley. Well, the officers, every so many weeks—this is mentioned somewhere in this pile of papers—every so many weeks a lieutenant is appointed to give a foreign affairs lecture or a current affairs lecture, pardon me, to the troops, at which time he explains the world situation in a half hour. I remember having one second lieutenant telling us about Dalai Lama or it was a first lieutenant and I forget what he told us, but it was something completely absurd. I think at that time the Dalai Lama had just disappeared or something, and one would get the impression, I think, that he thought the Dalai Lama was a leader in Pakistan or something. Mr. Jenner. That is the impression the lieutenant tried to convey? Mr. Thornley. Well, I think that was the impression the lieutenant had had when he had been assigned to give this lecture. The last minute, he got down and started going through the news magazines to get his information, got it somewhat inaccurately, and didn't particularly care whether it was accurate or not anyway. Stood up in front of the troops and reeled off the lecture, and, of course, most of the enlisted men didn't know enough to criticize him either because they weren't that interested, and that was it—with a couple of people laughing up their sleeves, and this happened later, this didn't happen at the time I knew Oswald. However, in such a situation Oswald would have been careful I am sure to raise his hand and correct the lieutenant. Mr. Jenner. I was going to get to that. During the course of these lectures did the troops as you called them engage in discussion with the instructor?
  • 64.
    Mr. Thornley. Theywere permitted to ask questions, to raise their hands to ask questions. And Oswald would have probably asked a question which would have made light of the lieutenant's ignorance. Mr. Jenner. Put the lieutenant at a disadvantage? Mr. Thornley. Yes. Mr. Jenner. Were you present at any times when you were at El Toro when the lectures occurred when, at that time Oswald raised his hand and engaged in dissertation? Mr. Thornley. I might have been but I don't recall it if I was. I recall being present at several lectures at El Toro, and it just might have happened. It was the kind of thing Oswald would do and it wouldn't even have phased me. I probably wouldn't even have bothered to remember if it had happened. It would have been just part of the daily routine there so I would have—— Mr. Jenner. Did you ever engage in that sort of thing? Mr. Thornley. No; I never had guts enough to stand up and tell an officer he didn't know what he was talking about. Behind his back I might tell somebody that such-and-such officer didn't know what he was talking about, but I was never quite that brash—in that particular respect, anyway. Mr. Jenner. What were your impressions on Oswald being interested in music? Mr. Thornley. Not being interested in music myself particularly—— Mr. Jenner. I take it you had none; that is, any impressions as to his interests? Mr. Thornley. No, therefore, I had none; correct. Mr. Jenner. Did you ever play chess with him? Mr. Thornley. No. Mr. Jenner. Did you ever see him playing chess with anyone else?
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    Mr. Thornley. Justnow you mentioned the word "chess" as a definite association; I think he did play chess. I can't place the person. This—there were some other people in the outfit who played chess. There is one name I have been trying to remember for a long time, and I think it starts with "Win" something. "Winter" something. I'm probably way off base there. But a tall blond corporal, I believe, played chess and a couple of other men in the outfit played chess. At that time, I guess at that, I knew how to play chess. I have never been particularly interested, though, in the game so I don't—I am pretty sure I didn't play chess with him. In fact, come to think of it I had just been cured of playing chess 3 months before that; somebody beat me in about six moves and I stopped playing for about a year. It wasn't me. Mr. Jenner. While at El Toro did Oswald become engaged in any physical altercations with anybody? Mr. Thornley. No; definitely not to my knowledge. Never got into any fights or even any hot personal argument over anything, that I know of. Mr. Jenner. What was your impression, if you had one then, as to his disposition in that regard? Mr. Thornley. I had the impression that he avoided violence. Mr. Jenner. While you were at El Toro do you recall whether Oswald ever went off the base on liberty? Mr. Thornley. As far as I know he didn't. Mr. Jenner. Were there any discussions on the base as to what, if anything, Oswald did? Mr. Thornley. Not in my presence. Mr. Jenner. What, if anything, Oswald had done off the base on liberty? Mr. Thornley. Not in my presence.
  • 66.
    Mr. Jenner. Wasthere ever any discussion of Cuba and Castro and that problem? Mr. Thornley. Yes, sir. Mr. Jenner. All right; tell us all about that. Mr. Thornley. Well, at that time I and Oswald were both, and a couple of other men in the outfit, were quite sure that Castro was a great hero. Mr. Jenner. Why? Mr. Thornley. Well, he was liberating Cuba from Batista and, of course, we had heard all about Batista and what an evil man he was, which I am sure was true, and most of us had read some of the things written by Castro, some of Castro's promises—such as he would take no part in the government after the revolution, such things—so we had the definite impression—I remember there was one Puerto Rican boy, myself, Oswald, a couple of others who had quite an admiration for Castro, and thought the pro-Communist statements he was or might be making at the time, were made simply to guarantee a little more independence for his island because it was located so close to the United States. In other words, I felt at the time he was playing both ends against the middle in order to go his own way, something like Charles de Gaulle is doing right now by recognizing Red China. I felt it was purely statesmanship, statecraft, power politics. I didn't feel that Castro was a dedicated Communist. Whether Oswald did or not I don't know. He admired Castro because of the social reforms Castro was introducing. So did I at that time. Delgado, the Puerto Rican boy, as I recall it, was becoming worried at that time because he was beginning to think maybe Castro was communistic. I didn't think so. Oswald, as far as I know, didn't have anything to say on that matter. And that is about all I can tell you.
  • 67.
    Mr. Jenner. Well,you say that you admired Castro and you knew Oswald admired Castro. Tell us on what you base that comment. Mr. Thornley. Well, once again as I remember, there was one of these afternoon discussions once again, and somebody was saying something, worried about Castro, it might have been Delgado, it might have been somebody else, I don't think it was Delgado that day because I think he was defending Castro, somebody said something against Castro, and Oswald said that he didn't think Castro was so bad. He thought Castro was good for Cuba, and they said why, and I took up the argument, which was the argument I just gave you, the naive idea I had at the time that he was playing for independence, and Oswald remained silent, shaking his head affirmatively a couple of times, and that was it. Mr. Jenner. Shaking his head affirmatively with respect to the comments you were making? Mr. Thornley. Yes; to my argument, to my justification of Castro. Mr. Jenner. But you recall no provocative remarks that he made in that connection? Mr. Thornley. No. Mr. Jenner. Did Oswald have a nickname? Mr. Thornley. Not that I know of except Oz sometimes. Mr. Jenner. Did you ever hear him referred to as "Ozzie Rabbit"? Mr. Thornley. Well, yes; I didn't realize that anybody else referred to him as such but I always thought of him as such. He reminded me very much of a cartoon character at that time. It was kind of pathetic. There was something about this little smile of his, and his expression on his face and the shape of his head, just the general, his general appearance established a definite association in my mind with some Warner Bros. cartoon character, I believe Warner Bros. And I, very recently, in a discussion with someone, describing
  • 68.
    Oswald mentioned thathe reminded you of—I said: "I think there is a character called Oswald Rabbit who appears in movie cartoons." And they shook their head. Now, I know where I got that particular example so I probably heard him referred to as "Ozzie Rabbit," though I don't recall specifically. Mr. Jenner. Did he occasionally have a nickname or a reference made to him attendant upon his interest in the study of the Russian language or his interest in communism or in Russia or Soviet—— Mr. Thornley. Only he was sometimes called the Communist and he would, sometimes I know—as far as his study of the Russian language went he made no attempt to hide this. In fact, he made—would make attempts to show it off by speaking a little Russian. Mr. Jenner. He was proud of that, was he? Mr. Thornley. Yes; there was someone else in the outfit who spoke Russian, don't ask me who, they used to exchange a few comments in the morning at muster and say hello to each other or something, and he also would make jokes in Russian, not in Russian, but in English, in a thick Russian accent many times; this was very typical of him. Mr. Jenner. He resorted to that area and use of satire? Mr. Thornley. Yes; until I had made the comment that implied he was a Communist, I had no idea—— Mr. Jenner. That he was sensitive? Mr. Thornley. That he was sensitive about it because he didn't seem to be. Mr. Jenner. Did he have any visitors? Mr. Thornley. Not that I recall.
  • 69.
    Mr. Jenner. Wasthere any discussion at anytime about the possibility of his going to Russia? Mr. Thornley. No. Mr. Jenner. This was a complete surprise to you when you saw it in Stars and Stripes? Mr. Thornley. Somebody would say to him, "Why don't you go and live in Russia," in the middle of an argument. Mr. Jenner. I didn't mean that in that sense but did he volunteer a statement on his part about his going to Russia? Mr. Thornley. Never anything; no. Mr. Jenner. I take it it was your opinion he was not a Communist at the time he was assigned to El Toro? Mr. Thornley. That was my opinion. Mr. Jenner. I take it you have never seen or talked with Oswald subsequent to the time he left or you left for Japan, from El Toro? Mr. Thornley. No. Mr. Jenner. That is, my statement is correct. Mr. Thornley. Yes, sir. Mr. Jenner. It follows, I take it, that you were never aware that he was in New Orleans when you were there? Mr. Thornley. No; I wasn't. Mr. Jenner. You were not aware of his comings and goings other than the newspaper report that your folks sent you? Mr. Thornley. I was aware that he had come back from the Soviet Union and gone to Dallas, and I know I at that time did think about going to see him in Dallas for the book, to find out just why he did go to Russia, to check it with my own theory. Mr. Jenner. I am going to get to that in due course.
  • 70.
    Mr. Thornley. Butaside from knowing that he came back and went to live in Dallas with a Russian wife and a child I had no idea of his comings or goings. Mr. Jenner. At the time you had some notion of going to Dallas to see him or Fort Worth, as the case might be, it was with respect to the book you have talked about you were then in the process of writing or fulminating about? Mr. Thornley. Yes; it was practically—well, it was finished by that time but I was thinking about, I was definitely planning to rewrite it. I didn't know how soon, and I thought before I did rewrite it I would go talk to him and see what he could tell me about. There were a lot of gaps in the book, and in the book I was not able to explain how he got from the United States to Russia and things like that. A lot of things I wanted to check out and I thought if I could get him to cooperate with me, perhaps not even in telling him I was writing the book, I could get the information I wanted. Mr. Jenner. And this was the state of mind you had after you had heard that he returned to the United States? Mr. Thornley. Right. Mr. Jenner. Which was June of 1962, when he returned? Mr. Thornley. Right, and I had finished the book in February. Mr. Jenner. Of 1963? Mr. Thornley. 1962. Mr. Jenner. 1962. You were in Mexico and Mexico City in 1963? Mr. Thornley. Yes. Mr. Jenner. Cover that for us. What was the motivation, the length of the trip? Mr. Thornley. I will have to begin at the beginning on that. On April 17, my parents sent me a gift of $100 on the condition that I spend it for a bus ticket to visit them that summer. Which I did, and
  • 71.
    I left around—well,I arrived in California on May 5. I remember going along the border and seeing fireworks on the other side of the border. Mr. Jenner. What border? Mr. Thornley. From Yuma to San Diego. Mr. Jenner. Mexican border? Mr. Thornley. That is Cinco De Mayo. I arrived in California on May 5 and I stayed there until late August. Now, I think in one of these reports that I gave to the FBI the information might be different. Since then I have checked with notebooks that I kept of my activity, and I was on my way back to New Orleans in late August. I went by way of Mexico City because I have taken 5 years of Spanish in school and I never had the opportunity to live in an environment where I would have to use it, depend on it solely, and I wanted to see how I would do. I have always wanted to visit Mexico, to see Mexico City. I checked into the prices. I had found out I had enough money that I would be able to go down to Mexico City and stay a short while. So I went down there for about a week, actually it was 6 days I spent within Mexico, from Tijuana to Mexico City, on a Mexican bus, and then when my money began to run out from Mexico City to Matamoros or Brownsville, Tex., on a Mexican bus. At this time, on my way up on a bus to Matamoros, it was September 2, because I had that in my notes, I have some notes about the bus ride and the date September 2. And I went from Brownsville to New Orleans by way of either Greyhound or Continental. Mr. Jenner. When did you arrive in New Orleans? Mr. Thornley. I went directly to New Orleans, so I imagine I arrived in New Orleans on September 3, possibly September 4.
  • 72.
    Mr. Jenner. Sothat between approximately May 1, 1963, and September 4 and 5—— Mr. Thornley. Say May 3 to September 4. Mr. Jenner. You were not in New Orleans? Mr. Thornley. Right. Mr. Jenner. You were returning to your home in California? You stayed there for approximately a month or so? Mr. Thornley. Longer than that. Mr. Jenner. Longer than that. You then went to Mexico, Mexico City, and you then returned directly to New Orleans? Mr. Thornley. Yes, sir. Mr. Jenner. During none of that period of time did you have any contact with or hear anything about Oswald? Mr. Thornley. Definitely not. Mr. Jenner. You at one time at least were acquainted with a lady by the name of Sylvia Bortin? Mr. Thornley. Sylvia Bortin? Mr. Jenner. B-o-r-t-i-n. Mr. Thornley. Yes; this young lady, by the way—— Mr. Jenner. Where did she reside? Mr. Thornley. In Whittier, Calif., or at least last summer she did, I don't know where she resides now. This young lady, by the way, was mentioned in—her mention in this whole matter came out of a misunderstanding on my part of a question asked by the FBI agents. Mr. Jenner. All right. Would you explain that, please? Mr. Thornley. I don't recall what the question was—oh, yes, he had asked me something about, I believe it was the First Unitarian Church in Los Angeles. I had mentioned earlier at the time I was
  • 73.
    talking to Oswald,and knew Oswald, I had been going to the First Unitarian Church in Los Angeles. This is a group of quite far to the left people politically for the most part, and mentioned in order to explain my political relationship with Oswald, at that moment, and he began to ask me questions about the First Unitarian Church and I answered, and then he realized or understood or asked what Oswald's connection with the First Unitarian Church was and I explained to him that there was none. Miss Bortin never knew Oswald and vice versa, and these people were two different parts of my life. There was this civilian compartment and the military compartment, and I never intermingled them. Mr. Jenner. This young lady married and her husband is now in Havana, Cuba? Mr. Thornley. That is what she told me last summer; yes. He was going to school in Cuba. Mr. Jenner. I take it this had nothing to do with yourself and Oswald's views with respect to Castro that you told us about. Mr. Thornley. No; this happened, I think, later, in fact I am sure it happened later. At that time Miss Bortin, she was then unmarried, did not know Robert Uname, I believe. I met him, I believe, September a year later. Mr. Jenner. Had you finished that? Mr. Thornley. Yes. Mr. Jenner. I take it that Oswald had no close personal friends at least that you observed? Mr. Thornley. That is correct. And the name of his closest friends I do not know. I do remember he had a close acquaintance that he seemed to get along with pretty well. Mr. Jenner. In the unit? Mr. Thornley. Yes; but I don't recall this man's name. If it was mentioned to me, I probably could, but——
  • 74.
    Mr. Jenner. Youwere groping for it when you were interviewed. You suggested it might be Charles—— Mr. Thornley. I mentioned a Charles. Mr. Jenner. Weis. Mr. Thornley. Weir, but that was not the man. This was a friend of a friend of the friend or a man who could give them that information perhaps that I couldn't. At this time perhaps, also, I was thinking of a possibility it might have been Weir and since then I have remembered definitely who Weir was. Mr. Jenner. Who was he? Mr. Thornley. I don't remember whether his first name was Charles but I remember who he was. Mr. Jenner. He was a noncom? Mr. Thornley. There was a man named Cooley. There was somebody else, and these are my associations, but who it was who used to talk Russian in the ranks with Oswald in the morning I don't know, but that is who it was. Mr. Jenner. Is this particular man you now mentioned the man who occasionally talked Russian with Oswald in the ranks, is he the man who you had in mind? Mr. Thornley. Yes. Mr. Jenner. As having been a friend of Oswald's? Mr. Thornley. Yes; in that in the same respect that I was a friend of Oswald's. Once, again, the exact terminology I would use would be close acquaintance. Mr. Jenner. Yes; I would say from your description of the relationship with Oswald that it was more an acquaintanceship than a friendship.
  • 75.
    Mr. Thornley. Ithink it was probably the same with this person from what I recall, to my knowledge. Mr. Jenner. In other words, when you say friend, he wasn't a buddy of Oswald? Mr. Thornley. No; Oswald was not the type of person who had, as it has been emphasized on all parts, I think, and it confirms my own impression, was not the type of person who made close friends or who stuck with close friends. Mr. Jenner. You saw no instance in which Oswald evidenced affection for anybody, I mean in the nice sense of the word? Mr. Thornley. No; none whatsoever. Mr. Jenner. Or anybody evidenced any affection in the nice sense of the word for him? Mr. Thornley. No. Mr. Jenner. I take it your trip to Mexico City was purely one of general interest as you have described and had nothing to do with any interest on your part in going to Cuba or attempting to go to Cuba? Mr. Thornley. Believe me, no. I have no desire to go to Cuba unless I am going to take a rifle and be on an invasion force or something. Mr. Jenner. Did you hear of anybody in the Marine Corps, whose last name was Hidell? Mr. Thornley. At the time this name was mentioned to me that was—that person, whoever it was that Oswald used to speak to in the ranks in the morning came to my mind. But I can't say that that was the name, and I am—of course, now, I am very leery that that —very uncertain as to ever having heard the name Hidell, and I doubt it very much. Mr. Jenner. Shortly after the unfortunate occurrence of November 22, 1963, you were interviewed by Secret Service agents, were you
  • 76.
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