JDBC in JAVA 3

JDBC in JAVA 3

Steps to connect a Java Application to Database

The following 5 steps are the basic steps involve in connecting a Java application with Database using JDBC.

1. Register the Driver

2. Create a Connection

3. Create SQL Statement

4. Execute SQL Statement

5. Closing the connection
 

Register the Driver

Class.forName() is used to load the driver class explicitly.

Example to register with JDBC-ODBC Driver

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

Create a Connection

getConnection() method of DriverManager class is used to create a connection.

getConnection() method of DriverManager class is used to create a connection.

Syntax:

getConnection(String url)
getConnection(String url, String username, String password)
getConnection(String url, Properties info)

Example establish connection with Oracle Driver

Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE","username","password");

Create SQL Statement

createStatement() method is invoked on current Connection object to create a SQL Statement.

Syntax

public Statement createStatement() throws SQLException

Example to create a SQL statement

Statement s=con.createStatement();

Execute SQL Statement.

executeQuery() method of Statement interface is used to execute SQL statements.

Syntax:

public ResultSet executeQuery(String query) throws SQLException

Example to execute a SQL statement

ResultSet rs=s.executeQuery("select * from user");
  while(rs.next())
  {
   System.out.println(rs.getString(1)+" "+rs.getString(2));
  }

Closing the connection

After executing SQL statement you need to close the connection and release the session. The close() method of Connection interface is used to close the connection.

Syntax:

public void close() throws SQLException

Example of closing a connection:

con.close();