Query pulling wrong records

Donovan · Client Joined: Oct 07, 2003 Posts: 691 Location: Ohio

I have a page that looks at which students have not yet submitted a Peer Evaluation of their fellow team mates. The issue I am having is it seems I pull the same number of students no matter which course I look at. The match on Course_Year = Class_Year works as I only pull 2nd year students for 2nd year courses. But if I look at other 2nd year courses I pull the same students even though that course has not had any peer evaluations yet.

I pass this to the page and it is accurate.

$Course_Number = intval($_GET['Course_Number']);

But my query is in error somewhere. I am pulling all those students who have not yet submitted a peer evaluation but WHERE c.Course_Number = '$Course_Number' does not seem to be working correctly.

Code:

$getpendingevals = $db->sql_query("SELECT * FROM ".$prefix."_tl_students a
LEFT JOIN ".$prefix."_tl_peereval b ON (a.LDAP_USER = b.rater)
JOIN ".$prefix."_tl_courses c
WHERE c.Course_Number = '$Course_Number'
AND c.Course_Year = a.Class_Year
AND b.rater IS NULL
ORDER BY a.Name_Last");

mars · Posted: Wed Sep 10, 2008 4:33 pm

Not having the tables and data to go by locally here I would say it is because you are LEFT JOINING on b.rater while looking for that same field to be NULL?