Details
Bug
Closed
Minor
Description
I was executing a lot of cron scripts while playing with another bugs and then, sometimes, I've got this errror, related to tags:
ERROR: column "nr" does not exist
SELECT tb.tagid , COUNT
AS nr FROM mdl_tag_instance ta INNER JOIN mdl_tag_instance tb ON ta.itemid = tb.itemid WHERE ta.tagid = 1 AND tb.tagid != 1 GROUP BY tb.tagid HAVING nr > 2 ORDER BY nr DESC
line 686 of lib/dmllib.php: call to debugging()
line 966 of lib/dmllib.php: call to get_recordset_sql()
line 775 of tag/lib.php: call to get_records_sql()
line 807 of tag/lib.php: call to tag_compute_correlations()
line 369 of admin/cron.php: call to tag_cron()
Using PostgreSQL (not tested under other DBs)
Ciao 
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We were having the same problem under Moodle 1.9.1 and PostgreSQL 8.1 but the ORDER clause wasn't the issue it was the HAVING one. Here's a patch that sorted this problem out for us and stopped the Errors:
diff --git a/tag/lib.php b/tag/lib.php
— a/tag/lib.php
+++ b/tag/lib.php
@@ -765,7 +765,7 @@ function tag_compute_correlations($min_correlation=2) {
"FROM {$CFG->prefix}tag_instance ta INNER JOIN {$CFG->prefix}tag_instance tb ON ta.itemid = tb.itemid ".
"WHERE ta.tagid = {$tag->id} AND tb.tagid != {$tag->id} ".
"GROUP BY tb.tagid ".
- "HAVING nr > $min_correlation ".
+ "HAVING COUNT > $min_correlation ".
"ORDER BY nr DESC";
- "HAVING nr > $min_correlation ".
+ "HAVING COUNT > $min_correlation ".
"ORDER BY nr DESC";
pg does not support aliases in ORDER BY, right?
--> ORDER BY COUNT
DESC