try {
   // Retrieving rows from the database.
   PreparedStatement stmt = 
     connection.prepareStatement(
       "SELECT * FROM mytable WHERE COL_A = ?");
   int colunm = 1;
   stmt.setString(colunm, "Patrick Chan");
   ResultSet rs = stmt.executeQuery();
 
   // Updating the database.
   stmt = connection.prepareStatement(
     "UPDATE mytable SET COL_A = 
       ? WHERE COL_B = ?");
   colunm = 1;
   stmt.setString(colunm, "John Doe");
   colunm = 2;
   stmt.setInt(colunm, 123);
   int numUpdated = stmt.executeUpdate();
 } catch (SQLException e) {
 }