Duplicate fix that will work on MSSQL

locallib.php

@@ -1135,7 +1135,12 @@ class attendance {
             $where = "ats.attendanceid = :aid AND ats.sessdate >= :csdate";
         }
 
-        $sql = "SELECT ats.id, ats.groupid, ats.sessdate, ats.duration, ats.description, al.statusid, al.remarks
+        // We need to add this concatination so that moodle will use it as the array index that is a string.
+        // If the array's index is a number it will not merge entries.
+        // It would be better as a UNION query butunfortunatly MS SQL does not seem to support doing a DISTINCT on a the description field.
+        $id = $DB->sql_concat(':value', 'ats.id');
+
+        $sql = "SELECT $id, ats.id, ats.groupid, ats.sessdate, ats.duration, ats.description, al.statusid, al.remarks
                   FROM {attendance_sessions} ats
             RIGHT JOIN {attendance_log} al
                     ON ats.id = al.sessionid AND al.studentid = :uid
@@ -1147,7 +1152,8 @@ class attendance {
                 'aid'       => $this->id,
                 'csdate'    => $this->course->startdate,
                 'sdate'     => $this->pageparams->startdate,
-                'edate'     => $this->pageparams->enddate);
+                'edate'     => $this->pageparams->enddate,
+                'value'     => 'c');
         $sessions = $DB->get_records_sql($sql, $params);
 
         // All sessions for current groups.
@@ -1163,7 +1169,7 @@ class attendance {
             $where = "ats.attendanceid = :aid AND ats.sessdate >= :csdate AND ats.groupid $gsql";
         }
 
-        $sql = "SELECT ats.id, ats.groupid, ats.sessdate, ats.duration, ats.description, al.statusid, al.remarks
+        $sql = "SELECT $id, ats.id, ats.groupid, ats.sessdate, ats.duration, ats.description, al.statusid, al.remarks
                   FROM {attendance_sessions} ats
              LEFT JOIN {attendance_log} al
                     ON ats.id = al.sessionid AND al.studentid = :uid