Execute Multiple JDBC Queries In a Defined Sequence - mysql

Question

I'm develop an application to connect MySQL via JDBC. In an action, I need to execute two queries, sql to read, and sql to update.
To make sure, sql to read query would be executed first, and sql to update to be executed later, I use JDBC transaction. But somehow, the problem is, mysql execute 2nd query first, and then the first read query.
Looking for suggestions. Many thanks.
// Sql connection
Connection conn = null;
Statement stmt = null;
PreparedStatement preparedStatement = null;
PreparedStatement preparedStatementUpdate = null;
String sql = "SELECT item_name, item_detail FROM Order_Printing where kitchen_id = ? and order_printed = ?";
String sqlFlag = "UPDATE order_printing set order_printed = 1 where kitchen_id = ?";
try {
// Register JDBC driver (Note to add mysql connector jar file)
Class.forName("com.mysql.jdbc.Driver");
// Step 3: open a connection
conn = DriverManager.getConnection(DB_URL, USER, PASS);
conn.setAutoCommit(false); // Disable auto-commit mode
preparedStatement = conn.prepareStatement(sql);
preparedStatement.setInt(1, 4);
preparedStatement.setInt(2, 0);
ResultSet rs = preparedStatement.executeQuery();
//
preparedStatementUpdate = conn.prepareStatement(sqlFlag);
preparedStatementUpdate.setInt(1, 4);
preparedStatementUpdate.executeUpdate();
int startingPos = 10;
int orderNumber = 1;
while (rs.next()) {
String item_name = "Order " + orderNumber++ + ": ";
item_name += rs.getString("item_name");
String item_detail = rs.getString("item_detail");
startingPos += 20;
g.drawString(item_name, 0, startingPos);
startingPos += 20;
g.drawString(item_detail, 0, startingPos);
}
conn.commit();
} catch (SQLException se) {
se.printStackTrace();
} catch (ClassNotFoundException se) {
se.printStackTrace();
} catch (Exception se) {
se.printStackTrace();
} finally{
//finally block used to close resources
try{
if(stmt!=null)
conn.close();
}catch(SQLException se){
}// do nothing
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}
}

Answer 1

Try executing rs.next() while loop BEFORE you call preparedStatementUpdate.executeUpdate();