fix 课程时间

zhongzheng-system/src/main/resources/mapper/modules/course/CourseMapper.xml

@@ -521,7 +521,8 @@
             cg.class_status,
             cg.status,
             cg.learning_status,
-            cgu.period_status
+            cgu.period_status,
+            cg.learning_time_start
         FROM
             class_grade_user cgu
                 LEFT JOIN class_grade cg on cgu.grade_id = cg.grade_id