Inner Join Error

[Nodral]

Hi

 

I have 3 tables in my DB which I am trying to interrogate.

 

mdl_feedback_completed has columns id, feedback, userid, timemodified

mdl_feedback_tracking has columns id, userid, feedback, completed

mdl_feedback_value has columns id, course_id, item, completed, value.

 

These tables are already set up as part of a Moodle installation and I cannot modify them.

 

The query I am trying to run should select value from mdl_feedback_value depending on the timemodified field in mdl_feedback_completed.

 

However, the query is timing out and I get a fatal error.

 

Any ideas?

 

$sql="SELECT mdl_feedback_value.value FROM mdl_feedback_value INNER JOIN mdl_feedback_tracking ON mdl_feedback_value.completed = mdl_feedback_tracking.completed INNER JOIN mdl_feedback_completed ON mdl_feedback_tracking.feedback = mdl_feedback_completed.feedback WHERE timemodified = 1301499189";

[kickstart]

Hi

 

The SQL looks OK and normally even with poor indexing I wouldn't expect it to be that slow.

 

My guess would be that there should be more columns used to JOIN the tables together (e, maybe userid between mdl_feedback_completed and mdl_feedback_tracking), and without this you are landing up getting a massive number of records (very easy for it to be in the millions).

 

All the best

 

Keith