我们如何在MySql查询的两个单独的字段中分配ORDER BY？

Question

how i set order by for two separate fields in mysql

CODE

$sql = 'SELECT q.question_id, a.answer_id, q.question_name, a.option_name, q.display_order AS ques_order, a.correct, a.display_order AS opt_order FROM questions q JOIN answers a ON (a.question_id = q.question_id) WHERE test_id = '.$m_test_id.' ORDER BY ques_order, opt_order ASC'; 

error message:

MysqlError: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ORDER BY ques_order, opt_order ASC' at line 4

ORDER BY ques_­order,­ opt_­order ASC;

Answer 1

There's something wrong with $m_test_id ; it's probably empty and causing issues with the SQL grammar. Consider using prepared statements:

$sql = 'SELECT q.question_id, a.answer_id, q.question_name, a.option_name, q.display_order AS 
    ques_order, a.correct, a.display_order AS opt_order 
    FROM questions q 
    JOIN answers a ON a.question_id = q.question_id 
    WHERE test_id = :test
    ORDER BY ques_order, opt_order ASC'; 

$stmt = $db->prepare($sql);
$stmt->execute(array(':test' => $m_test_id));

Besides that, you should find out why $m_test_id was empty in the first place.

If you're not using PDO or mysqli you can use mysql_real_escape_string() but note that it's deprecated and shouldn't be used anymore.