commit f9d52bd87fb052614d0ff0500ebd1b21f4c64272
Author: Fanmail Administrator <root@fanmail.com>
Date:   Tue Feb 19 11:33:14 2013 -0600

    fix duplicate GROUP BY in results SQL query when using postgresql

diff --git a/quiz.admin.inc b/quiz.admin.inc
index ea2c92d..5a42f60 100644
--- a/quiz.admin.inc
+++ b/quiz.admin.inc
@@ -2138,9 +2138,10 @@ function _quiz_results_mr_prepare_filter($quiz) {
                            WHERE qnrs.nid = :quiz_nid " . $filter['where'] . "
                            GROUP BY qnrs.uid
                          ) AS qnrc ON qnrs.uid = qnrc.uid AND qnrs.score = qnrc.top_score";
-    $filter['group'] .= " GROUP BY qnrs.uid";
     if (db_driver() == 'pgsql') {
       $filter['group'] .= " GROUP BY qnrs.uid, u.uid, u.name, qnrs.result_id, qnrs.score, qnrs.is_evaluated, qnrs.time_start, qnrs.time_end, qnp.pass_rate";
+    } else {
+      $filter['group'] .= " GROUP BY qnrs.uid";
     }
   }
   return $filter;