diff --git a/Dao/MyBatis/Maps/CRoom.xml b/Dao/MyBatis/Maps/CRoom.xml
index 8318b83..01fd993 100644
--- a/Dao/MyBatis/Maps/CRoom.xml
+++ b/Dao/MyBatis/Maps/CRoom.xml
@@ -296,7 +296,7 @@
             ,a.totstudy=d.totstudy
             ,a.etime=now()
             ,a.istatus=case when a.istatus <> 2  and c.atime * 60 <= d.totstudy then 2 else a.istatus end
-            ,a.finishtime=case when a.finishtime is null  and c.atime * 60 <= d.totstudy then now() else null end
+            ,a.finishtime=case when a.finishtime is null  and c.atime * 60 <= d.totstudy then now() else a.finishtime end
             ,a.eip=#uip#,a.ispce=#ispc#
             ,a.psec=#psec#
             where a.lectno=#lectno# and a.cmino=#cmino#;