รบกวนช่วยเขียนโค๊ด select ทีครับคิดไม่ออกเลย ใกล้ส่งโปรเจคจบแล้วด้วย

$rs=$db->query("select id_type, code_type from jobtype");
$qr = '';
while( $ro = $rs->fetch_assoc()){
 $qr .= ($qr? ',' : '') . "sum(if(id_type=$ro[id_type], total, 0)) as $ro[code_type] ";   
}

$sql = "select name, $qr from (
SELECT u.id_user, u.name, jd.id_type,  TIMEDIFF( jd.timeend, jd.timestart ) AS total
FROM jobdata jd
LEFT JOIN user u ON  u.id_user = jd.id_user 
) as tmp 
group by id_user ";