Getting started with JDBC

After installing the driver establishing a JDBC connection can be done as follow:

• JDBC Package Import
• Formulation of Database URL
• Connection Object Creation
• JDBC driver Register

JDBC Package Import:

Import statement is placed at beginning source code to inform java complier to check classes and reference. The JDBC packages allow select, update, delete and insert data into SQL tables.

import java.sql.* ;  // JDBC programs standard
import java.math.* ;

Register JDBC Driver:

Loading Oracle driver's class file into memory is the part of registering driver process. The registration should be done only once in program. The registration process can be done two ways :

First:

Java's Class.forName() method dynamically load the driver's class file in memory which registers automatically .

try {
   Class.forName("oracle.jdbc.driver.OracleDriver");
}
catch(ClassNotFoundException ex) {
   System.out.println("Error: loading driver class failed!");
   System.exit(1);
}

Second:

The second approach allow to register driver using the static DriverManager.registerDriver() method.

try {
   Driver myODriver = new oracle.jdbc.driver.OracleDriver();
   DriverManager.registerDriver(myODriver);
}
catch(ClassNotFoundException ex) {
   System.out.println("Error: unable to load oracle Driver!");
   System.exit(1);
}

Formulation Database URL:

After  driver is loaded connection is established using DriverManager.getConnection() method which has three overloaded methods:

• getConnection(String url, Properties prop)
• getConnection(String url)
• getConnection(String url, String user, String password)

JDBC driver and URL format:

Connection Object Creation:

The connection of object creation can be done in 3 different ways:

• Database URL with username and password: The DriverManager.getConnection() requires database URL, username and password.

       String connection_url = "jdbc:oracle:thin:@abc:1521:Users";
         String UserName = "db_username";
         String Pwd = "db_password"
         Connection conn = DriverManager.getConnection(connection_url, UserName, Pwd);

• Use only database URL: 
  
  In this DriverManager.getConnection( ) requires passing string url includes username and password following form: jdbc:oracle:driver:username/password@database

• Properties object and database URL : In this getConnection( ) method requires Properties object and database URL.
  
  DriverManager.getConnection(String url, Properties info);
  

  import java.util.*;
  String URL = " jdbc:oracle:thin:@abc:1521:Users";
  Properties info = new Properties( );
  info.put( "user", "db_username" );
  info.put( "password", "db_password" );
  Connection conn1 = DriverManager.getConnection(URL, info);

Closing JDBC connections:

At end of JDBC program it requires explicitly close all connections to the database to each database session. Closing the connection should be done in Finally block so that it gets executed regardless of exception occurs or not.

conn1.close();