Steps to connect to the Database in java

We have six steps to connect to the database in java. The following steps are used by Java programmers while using jdbc in their java programs.

1.   Registering  the driver

2.   Creating connection

3.   Creating statement

4.   Executing queries

5.   Retrieving the Results

6.   Closing connection

1. Registering  the driver :

There are several drivers available in the market we should first declare a driver which is going to be used for communication with the database server in a java program.

Registering  the driver in 4  ways:

1. By creating an object to Driver class of the driver software.

Example :

com.mysql.jdbc.Driver driver obj=new com.mysql.jdbc.Driver();

2. By sending the driver class object to registerDriver () method of DriverManger class.

Example :

DriverManager.registerDriver(new com.mysql.jdbc.Driver());

3. By sending the driver class name directly to forName () method.

Example :

Class.forName(com.mysql.jdbc.Driver());

4. By passing the driver at the time of running the program we can use getProperty () method of the System class.

Example :

String dName = System.getProperty("driver");

Class.forName(dName);

We pass the command line arguments

Example :

c:\> java-d  driver = driverclassname program name.

2. Creating connection :

The getConnection () method of DriverManager class is used to establish connection with the database.

We pass three arguments through the getConnection () method.

URL of the Database.

Username.

Password.

Example : 

DriverManager.getConnection("com.mysql.jdbc.Driver", "root", "root");

3. Creating statement :

The createStatement () method of Connection interface is used to create Statement.

The object of the statement is responsible to execute queries to the database.

Example :  

Statement st=con.createStatement();

4. Executing queries :

The executeQuery () method of Statement interface is used to execute Queries to the database.

This method returns the object of ResultSet that can be used to get all the records of a table.

Example :

public ResultSer rs=st.executeQuery("select * from Emp");

5. Retrieving the Results :

The Result obtained by executing SQL Statements can be stored in an object with the help of interfaces like ResultSet () method, resultSetMetaData () and dataBaseMetaData ().

Example :

          ResultSer rs=st.executeQuery("select * from Emp");

          while(rs.next())

          {

          System.out.println(rs.getInt(1)+""+rs.getString(2));

          }

6. Closing connection :

By using the close() method of Connection interface is used to close the 

connection.

By closing the connection object statement and ResultSet will be closed automatically.

Example :  

con.close();

Connect to the database in jdbc :

Example :

package com.wins.jdbc;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.SQLException;

public class Connectiondatabase

{

          public static void main(String[] args) throws SQLException

          {

                   System.out.println("This is simple jdbc connection program to connect the mysql database");

                  

 String username="root";

                   // the username is mysql database login username

                  

 String password="root";

                   // the password is mysql database  login password

                  

 String dbname="test";

                   // the dname is the database name or schema

                  

 String url="jdbc:mysql://localhost:3306/";

                   // the url is the address of the mysql database with port number the default port number is 3306

                  

 Connection conn=null;

                  

 DriverManager.registerDriver(new com.mysql.jdbc.Driver());

                   // registering the driver using second method

                  

 conn=DriverManager.getConnection(url+dbname,username,password);

                   // Creating the connection

                  

 System.out.println("successfully connected");

                  

 conn.close();

                   //Closing the connection

                  

 System.out.println("connection closed");

          }

}

Output :

           

Successfully connected

Connection closed

source technologiesleader