JDBC ppt

JDBC
Java Database Connectivity
Rohit Jain
DTU
B.Tech, Software Engineering

What is JDBC?
 JDBC API allows Java programs to
connect to DBs
 Provides cross-vendor connectivity and
data access across relational databases
from different vendors
 Classes and interfaces allow users to
access the database in a standard way
 The JVM uses the JDBC driver to
translate generalized JDBC calls into
vendor specific database calls

What Does JDBC Do ?
JDBC makes it possible to do three things:
Establish a connection with a database
Send SQL statements
Process the results.

JDBC Classes for DB
Connection
 java.sql.Driver
◦ Unless creating custom JDBC implementation, never
have to deal with it. It gives JDBC a launching point
for DB connectivity by responding to
DriverManager connection requests
 java.sql.DriverManager
◦ Maintains a list of Driver implementations and
presents an application with one that matches a
requested URL.
◦ getConnection(url, uid, password)
◦ getDrivers(), registerDriver()
 java.sql.Connection
◦ Represents a single logical DB connection; used for
sending SQL statements

JDBC Drivers
 JDBC-ODBC bridge
 Part Java, Part Native Driver
 Intermediate DAccess Server
 Pure Java Drivers

Driver Manager
 The purpose of the
java.sql.DriverManger class in JDBC is
to provide a common access layer on top
of different database drivers used in an
application
 DriverManager requires that each driver
required by the application must be
registered before use
 Load the database driver using
ClassLoader
 Class.forName(“oracle.jdbc.driver.Oracle
Driver”);

Registering a JDBC Driver
 Driver must be registered before it is
used.
 Drivers can be registered in three
ways.

Most Common Approach is
 To use Java’s Class.forName()
 Dynamically loads the driver’s class
file into memory
 Preferable because
It allows driver registration
configurable and portable.

 The second approach you can use to
register a driver is to use the static
DriverManager.registerDriver( )
method.
 Use the registerDriver( ) method if
you
are using a non-JDK compliant JVM.
For example:
DriverManager.registerDriver(new
oracle.jdbc.driver.OracleDriver( ));

 The third approach is to use a
combination of Class.forName( ) to
dynamically load the Oracle driver and
then the driver classes' getInstance( )
method to work around noncompliant
JVMs.
 For example:
Class.forName("oracle.jdbc.driver.Oracle
Driver").newInstance();

Basic steps to use
a database in Java
 Establish a connection
 Create JDBC Statements
 Execute SQL Statements
 GET ResultSet
 Close connections

1. Establish a connection
 import java.sql.*;
 Load the vendor specific driver
◦ Class.forName("oracle.jdbc.driver.OracleDriver");
 What do you think this statement does, and how?
 Dynamically loads a driver class, for Oracle database
 Make the connection
◦ Connection con = DriverManager.getConnection(
"jdbc:oracle:thin:@oracle-prod:1521:OPROD", username,
passwd);
 What do you think this statement does?
 Establishes connection to database by obtaining
a Connection object

2. Create JDBC statement(s)
 Statement stmt = con.createStatement()
;
 Creates a Statement object for
sending SQL statements to the
database

3.Executing SQL Statements
 String createStudent = "Create table
Student " +
"(SSN Integer not null, Name
VARCHAR(32), " + "Marks Integer)";
stmt.executeUpdate(createStudent);
//What does this statement do?
 String insertStudent = "Insert into
Student values“ +
"(123456789,abc,100)";
stmt.executeUpdate(insertStudent);

Execute Statements
 This uses executeUpdate because the
SQL statement contained in
createTableCoffees is a data definition
language ( DDL ) statement
 DDL statements are executed with
executeUpdate
– Create a table
– Alter a table
– Drop a table
 executeUpdate is also used to execute
SQL statements that update a table

Execute Statements
 executeUpdate is used far more often
to update tables than to create them–
We create a table once but update it
many times
 The method used most often for
executing SQL statements is
executeQuery
 executeQuery is used to execute
SELECT statements – SELECT
statements are the most common SQL
statements

Entering Data to a Table
 Statement stmt = con.createStatement();
 stmt.executeUpdate ( "INSERT INTO COFFEES
" +
"VALUES ('Colombian', 101, 7.99, 0, 0)");
 stmt.executeUpdate ("INSERT INTO COFFEES "
+
"VALUES ('French_Roast', 49, 8.99, 0, 0)");
+
"VALUES ('Espresso', 150, 9.99, 0, 0)");
+
"VALUES ('Colombian Decaf' 101 8 99 0 0)");
+

Batch Update
 What is batch update?
- Send multiple update statement in a
single request to the database
 Why batch update?
-Better performance
 How do we perform batch update?
-Statement.addBatch (sqlString);
- Statement.executeBatch();

4.Get ResultSet
String queryStudent = "select * from Student";
ResultSet rs =
Stmt.executeQuery(queryStudent);
//What does this statement do?
while (rs.next()) {
int ssn = rs.getInt("SSN");
String name = rs.getString("NAME");
int marks = rs.getInt("MARKS");
}

5. Close connection
 stmt.close();
 con.close();

Sample Program
import java.sql.*;
class TestThinApp {
public static void main (String args[])
throws ClassNotFoundException,
SQLException {
Class.forName("oracle.jdbc.driver.OracleDriver
");
// or you can use:
DriverManager.registerDriver(new
oracle.jdbc.driver.OracleDriver());
Connection conn =
DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:xe","scott","ti

Statement stmt = conn.createStatement( );
ResultSet rset = stmt.executeQuery(
"select 'Hello Thin driver tester '||USER||'!'
result from dual");
while(rset.next( ))
System.out.println(rset.getString(1));
rset.close( );
stmt.close( );
conn.close( );
}
}

SUMMARY
 JDBC makes it very easy to connect
to DBMS and to manipulate the data
in it.
 You have to install the oracle driver in
order to make the connection.
 It is crucial to setup PATH and
CLASSPATH properly

JDBC ppt

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