JDBC FUNDAMENTAL

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

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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");

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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");

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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();

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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));
  }

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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();

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