Index: lib.php
===================================================================
--- lib.php     (revision 170)
+++ lib.php     (revision 177)
@@ -835,30 +835,60 @@
 }
 
 // sorting functions for grades
+
 function grade_sort_by_lastname($x,$y)
 {
+  return _grade_sort_by_names($x, $y, 'lastname asc, firstname asc');
+}
+
+function grade_sort_by_firstname($x,$y)
+{
+
+  return _grade_sort_by_names($x, $y, 'firstname asc, lastname asc');
+}
+
+function _grade_sort_by_names($x, $y, $sort)
+{
+    global $CFG;
     //$grades_by_student["$student->userid"]['student_data']['firstname'] = $student->firstname;
     //$grades_by_student["$student->userid"]['student_data']['lastname'] = $student->lastname;
+    /*
+       rherbst - strnatcascmp does not work in the way as SQL "order by" works. So the output
+       is different from the Excel/ODS/Text-Export.
     if (strnatcasecmp($x['student_data']['lastname'],$y['student_data']['lastname']) == 0) {
         return strnatcasecmp($x['student_data']['firstname'],$y['student_data']['firstname']);
     }
     else {
         return strnatcasecmp($x['student_data']['lastname'],$y['student_data']['lastname']);
     }
-}
+    */
+    if ($x['student_data']['lastname'] == $y['student_data']['lastname'] 
+       && $x['student_data']['firstname'] == $y['student_data']['firstname']) {
+      // no need to go to the database
+      return 0;
+    }
 
-function grade_sort_by_firstname($x,$y)
-{
-    //$grades_by_student["$student->userid"]['student_data']['firstname'] = $student->firstname;
-    //$grades_by_student["$student->userid"]['student_data']['lastname'] = $student->lastname;
-    if (strnatcasecmp($x['student_data']['firstname'],$y['student_data']['firstname']) == 0) {
-        return strnatcasecmp($x['student_data']['lastname'],$y['student_data']['lastname']);
+    $sql = "SELECT distinct concat(u.firstname, ' ', u.lastname) as fullname, u.firstname, u.lastname FROM " . $CFG->prefix 
+               . "user u WHERE "
+               . " (firstname = '" . $x['student_data']['firstname'] . "' AND  lastname = '" .  $x['student_data']['lastname'] ."')"
+               . " OR (firstname = '" . $y['student_data']['firstname'] . "' AND  lastname = '" .  $y['student_data']['lastname'] ."')"
+               . " ORDER BY $sort";
+    $rows = get_records_sql($sql);
+
+    if (count($rows) < 2) {
+      error(get_string("Not enough rows (" . count($rows) . ") records returned from db for sql: $sql;"));
     }
+
+    $firstrow = array_shift($rows);
+    if ($firstrow->lastname == $x['student_data']['lastname'] && $firstrow->firstname == $x['student_data']['firstname']) {
+      return -1;
+    }
     else {
-        return strnatcasecmp($x['student_data']['firstname'],$y['student_data']['firstname']);
+      return 1;
     }
 }