import java.sql.*;
import java.lang.*;
import java.io.*;

class  Ex_8_5_1_f {

    public static void main(String[] argv) throws Exception
    {
	Class.forName("com.mysql.jdbc.Driver").newInstance();
	Connection conn = DriverManager.getConnection(
                   "jdbc:mysql://amigo/rolf?user=rolf&password=rolf");

	Statement stmt = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY,
					      ResultSet.CONCUR_UPDATABLE);

	conn.setAutoCommit(false);
	conn.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);

	ResultSet uprs = stmt.executeQuery("SELECT * FROM PC");

	// Note: for updatable resultsets, only SELECT from one table,
	// Selected rows must include all primary keys (a primary key
	// must therefore exist in table).


	while (uprs.next()){

	    uprs.updateInt("price", uprs.getInt("price") - 100);
	    uprs.updateRow();

	}

	conn.commit();
    }

}