fix bug

stmms-biz/src/main/java/cn/com/qmth/stmms/biz/exam/service/impl/ExamStudentServiceImpl.java

@@ -259,6 +259,11 @@ public class ExamStudentServiceImpl extends BaseQueryService<ExamStudent> implem
 
     public ExamStudentSearchQuery findByQuery(final ExamStudentSearchQuery query) {
         checkQuery(query);
+        if (query.getSort() == null) {
+            query.orderById();
+        } else {
+            query.setSort(query.getSort().and(new Sort("id")));
+        }
         if (query.getSheetCount() != null) {
             query.setSheetCount(query.getSheetCount() * 2);
         }