recommended JDBC coding pattern

Note that connections, statements, and resultsets often tie up operating system resources such as sockets or file descriptors. In the case of connections to remote database servers, further resources are tied up on the server, eg. cursors for currently open resultsets. It is vital to close() any JDBC object as soon as it has played its part; garbage collection should not be relied upon. Forgetting to close() things properly results in spurious errors and misbehaviour. The above try-finally construct is a recommended code pattern to use with JDBC objects.

Statement stmt = conn.createStatement();
try {
   stmt.executeUpdate( "INSERT INTO MyTable( name ) VALUES ( 'my name' ) " );
} finally {
   //It's important to close the statement when you are done with it
   stmt.close();
}

Data is retrieved from the database using a database query mechanism. The example below shows creating a statement and executing a query.

Statement stmt = conn.createStatement();
try {
   ResultSet rs = stmt.executeQuery( "SELECT * FROM MyTable" );
   try {
       while ( rs.next() ) {
           int numColumns = rs.getMetaData().getColumnCount();
           for ( int i = 1 ; i <= numColumns ; i++ ) {
              //Column numbers start at 1.
              //Also there are many methods on the result set to return
              // the column as a particular type. Refer to the Sun documentation
              // for the list of valid conversions.
              System.out.println( "COLUMN " + i + " = " + rs.getObject(i) );
           }
       }
   } finally {
       rs.close();
   }
} finally {
   stmt.close();
}