Fix for sessions with taken attendance show twice in student report.

The two queries have been refactored into a single query using UNION

locallib.php

@@ -1101,50 +1101,46 @@ class attendance {
 
         // All taked sessions (including previous groups).
 
+        $groups = array_keys(groups_get_all_groups($this->course->id, $userid));
+        $groups[] = 0;
+        list($gsql, $gparams) = $DB->get_in_or_equal($groups, SQL_PARAMS_NAMED, 'gid0');
+
         if ($this->pageparams->startdate && $this->pageparams->enddate) {
             $where = "ats.attendanceid = :aid AND ats.sessdate >= :csdate AND
                       ats.sessdate >= :sdate AND ats.sessdate < :edate";
+            $where2 = "ats.attendanceid = :aid2 AND ats.sessdate >= :csdate2 AND
+                      ats.sessdate >= :sdate2 AND ats.sessdate < :edate2 AND ats.groupid $gsql";
         } else {
             $where = "ats.attendanceid = :aid AND ats.sessdate >= :csdate";
+            $where2 = "ats.attendanceid = :aid2 AND ats.sessdate >= :csdate2 AND ats.groupid $gsql";
         }
 
         $sql = "SELECT ats.id, ats.groupid, ats.sessdate, ats.duration, ats.description, al.statusid, al.remarks
                   FROM {attendance_sessions} ats
-            RIGHT JOIN {attendance_log} al
+                RIGHT JOIN {attendance_log} al
                     ON ats.id = al.sessionid AND al.studentid = :uid
                  WHERE $where
-              ORDER BY ats.sessdate ASC";
+            UNION
+                SELECT 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 = :uid2
+                 WHERE $where2
+             ORDER BY sessdate ASC";
 
         $params = array(
                 'uid'       => $userid,
                 'aid'       => $this->id,
                 'csdate'    => $this->course->startdate,
                 'sdate'     => $this->pageparams->startdate,
-                'edate'     => $this->pageparams->enddate);
+                'edate'     => $this->pageparams->enddate,
-        $sessions = $DB->get_records_sql($sql, $params);
+                'uid2'       => $userid,
-
+                'aid2'       => $this->id,
-        // All sessions for current groups.
+                'csdate2'    => $this->course->startdate,
-
+                'sdate2'     => $this->pageparams->startdate,
-        $groups = array_keys(groups_get_all_groups($this->course->id, $userid));
+                'edate2'     => $this->pageparams->enddate);
-        $groups[] = 0;
-        list($gsql, $gparams) = $DB->get_in_or_equal($groups, SQL_PARAMS_NAMED, 'gid0');
-
-        if ($this->pageparams->startdate && $this->pageparams->enddate) {
-            $where = "ats.attendanceid = :aid AND ats.sessdate >= :csdate AND
-                      ats.sessdate >= :sdate AND ats.sessdate < :edate AND ats.groupid $gsql";
-        } else {
-            $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
-                  FROM {attendance_sessions} ats
-             LEFT JOIN {attendance_log} al
-                    ON ats.id = al.sessionid AND al.studentid = :uid
-                 WHERE $where
-              ORDER BY ats.sessdate ASC";
-
         $params = array_merge($params, $gparams);
-        $sessions = array_merge($sessions, $DB->get_records_sql($sql, $params));
+        $sessions = $DB->get_records_sql($sql, $params);
 
         foreach ($sessions as $sess) {
             if (empty($sess->description)) {