Object oriented database

TOPIC
Object Oriented Database
Present By:
Md. Hasan Imam Bijoy
Student of C.S.E
Email: hasan15-11743@diu.edu.bd
Daffodil International University, Dhaka, Bangladesh.

Presentation Outline:
 Object Definitions
 Object Structures
 Object-Oriented Concepts
 Object-Oriented Databases
 Object Query Language(OQL) with Example
 Object-Oriented SQL
 Advantage of OODBS etc.

Definition of an Object
 Object – User defined complex data types
• An object has structure of state (variable) and methods
(behavior/operation)
 An Object is described by four characteristics:
• Identifier : a system-wide unique id for an object
• Name : an object may also have a unique name in DB
(optional)
• Lifetime: determines if the object is persistent or transient
• Structure: Construction of objects using type constructor

Object Structure
The State (current value) of a complex object may be constructed
from other objects (or other vales) by suing certain type
constructor
Can be represent by (I,C,V)
 I is an unique id
 C is a type constructor
 V is the object state
Basic types : Atom, tuple and set
Collection type : list, bag and array

Object Oriented Concept
Abstract Data Types
 Class definition, provide extension to complex attribute types
Encapsulation
 Implementation of operation and object structure hidden
 Inheritance
 Sharing of data withing hierarchy scope, support code
reusability
Polymorphism
 Operator overloading

Object Oriented Database
Abstract Data Types
 A database system that incorporates all the important
object-oriented concepts
 Some additional feature
 Unique Object identifiers
 Persistent object handling

Object Query Language (OQL)
Declarative Query Language
 Not Computationally Complete
 Syntax based on SQL(Select, from where)
 Additional flexibility (queries with user defined operators and types)

Example of OQL
The following is a sample query
“what ate the name of the black product?”
Select distinct p.name
From Products p
Where p.color = “Black”
 Valid in both SQL and OQL, but result are different .

Result of the Query (SQL)
Product No Name Color
P1 Ford Mustang Black
P2 Toyota Celica Green
P3 Mercedes SLK Black
Result:
Name
Ford Mustang
Mercedes SLK
 The statement queries a relational
database
 Returns a table with rows
Original Table:

Result of the Query (OQL)
Product No Name Color
P1 Ford Mustang Black
P2 Toyota Celica Green
P3 Mercedes SLK Black
Original Table:
Result:
String String
Ford Mustang Mercedes SLK
 The statement queries a object
oriented database
 Returns a collection of object

Comparison
Queries look very similar in SQL and OQL, sometimes they are the
same
In fact , the result they give are very different
Query returns:
OQL SQL
Object Tuple
Collection of Objects Table

Object Oriented SQL – SQL3
Foundation for OO database management systems –
ORACLE8, DB2, etc.
New features – “relation” & “Object oriented”
Relational Feature – new data types, new predicts,
enhanced semantics, additional security and an active
database
Object Oriented Features – support for functions and
procedures

User Define Datatypes
 Creating a “row type”
Example:
Create row type AddressType(
street char(50)
city char(20));
Create row type StarType(
Name char(30)
Address AddressType)

Creating Data types
 Creating “Table”
• Create table Address of type AddressType;
• Create table MovieStar of type StarType;
• Instances of Row types are tuples in table;

Sample Query
 Find the name and street addresses of those
MovieStars who stay in the city “Columbus”;
• Select MovieStar.name,
MovieStar.address.street
From MovieStar
Where MovieStar.address.city = “Columbus”;

Complex Data & Queries:
A Water Resource Management example
 A Database of state wide water projects
 Includes a library of picture sliders
 Indexing according to predefined concepts –
prohibitively expensive
 Type of Queries
 Geographic locations
 Reservoir levels during droughts
 Recent flood condition, etc.

Complex Data & Queries:
Addressing these queries
 Linking this database to landmarks on a topographic
map
 Examining the captions for each slide
 Implementing image-understanding programs
 Inspecting images and ascertaining attributes
These type of queries necessitate dedicated “methods”

Creating Function
 Create function one() returns int as “select 1 as RESULT”
language “SQL”
Select one() as answer:
Result
Answer
1

Creating “Table” & “Methods”
 Implementation:
Create tables slides(
id int,
date date,
Caption document,
pictureCD_Image,
method containsName
(name varchar)
return boolean
as external name “matching”
language ‘C’ );

Implementation
 Sample Query
Find a picture of a reservoir with lower level which
is in “Sacramento”
Select slides P, landmark L
Where isLowWaterLevel (P.picture) and
P.containsName (L.name) and L. name=“Sacramento”;

Object-Relational Mapping
 Object-Relational Mapping (ORM) systems built on top of traditional relational databases
 Implementor provides a mapping from objects to relations
 Objects are purely transient, no permanent object identity
 Objects can be retried from database
 System uses mapping to fetch relevant data from relations and construct objects
 Updated objects are stored back in database by generating corresponding update/insert/delete statements
 The Hibernate ORM system is widely used
 described in Section 9.4.2
 Provides API to start/end transactions, fetch objects, etc.
 Provides query language operating directly on object model
 queries translated to SQL
 Limitations: overheads, especially for bulk updates

Advantage of OODBMS
 Designer can specify the structure of objects and
their behavior (methods)
 Better interaction with object-oriented language
such as Java and C++
 Definition of complex and user-defined types
 Encapsulation of operations and user-defined
methods

A Water Resource Management example
 A Database of state wide water projects
 Includes a library of picture sliders
 Indexing according to predefined concepts –
prohibitively expensive
 Type of Queries
 Geographic locations
 Reservoir levels during droughts
 Recent flood condition, etc.

Object oriented database

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