JDBC Database Connections

What is JDBC ad Why do we need it?

·        It is an API Java DataBase Connectivity

·        Connect to the DataBase.

·        Retrieve Data from DataBase

·        Insert data into DataBase.

Steps for JDBC Program

o   Register a Driver

o   Connect to the DataBase

o   SQL Statements

o   Executing SQL Statements

o   Retrieving Results

o   Closing Connection

How to Register a Driver?

Option 1:

You can register a driver with the help of registerDriver() method.

For example,

DriverManger.registerDriver( new sun.jdbc.odbc.jdbcodbcDriver());

Option 2:

You can register a driver with the help of forName() method.

For example,

Class.forName(sun.jdbc.odbc.jdbcodbcDriver);

How To Connect To DataBase?

1.You should pass the URL of the DataBase.

2.You should give DataBase UserName.

3. You should give DataBase Password.

Please see the below code.

DriverManager.getConection(“jdbc:odbc:oradsn”, “scott”, “sa”);

How To Prepare SQL Statements?

Here you can use two ways.

1.Statement

2.Prepared Statement

For executing query we can use both, But the difference is Perpared Statement is Fast and It is Pre Compile.

Please look the below code.

Statement stmt = con.createStatement();

Now we have to execute the query with the help of executeQuery()  method.

ResultSet rs = stmt.executeQuery(“select * from vendor”);

Now the query will be executed and result will be stored into ResultSet.

ResultSet have some methods. You can use this for retrieving datas.

The methods are,

String getString()

int getInt()

float getFloat() etc.,.

How to use these methods, can see later in example.

Example Program for JDBC Connection:

import java.sql.*;

class TestJdbc {

          public static void main(String args[]) {

                   //Driver Register

          DriverManger.registerDriver( new sun.jdbc.odbc.jdbcodbcDriver());

          //Connection with database

Connection con =     DriverManager.getConnection(“jdbc:oracle:thin:@localhost:1521:     xe”, “test” , “sa”);

                   // for creating sql statement

                   Statemet stmt = con.createStatement();

                   //Executing statement

                   ResultSet rs = stmt.executeQuery(“Select * form vendor”);

                   // Retreiving results

                   While(rs.next()) {

                   System.out.pritln(“The vendor ID is ” + rs.getInt(1));

                   System.out.pritln(“Vendor Name ” + rs.getString());

                   System.out.pritln(“Vendor Fund Percent” + rs.getFloat());

                   }

con.close();

}

}