diff --git a/1787543922_table_series_add_deadline.up.sql b/1787543922_table_series_add_deadline.up.sql
index e8169e9..67f973d 100644
--- a/1787543922_table_series_add_deadline.up.sql
+++ b/1787543922_table_series_add_deadline.up.sql
@@ -1,2 +1,2 @@
 ALTER TABLE `course_series`
-ADD COLUMN `deadline` TIMESTAMP DEFAULT NULL COMMENT "报名截止时间" after `is_active`
\ No newline at end of file
+ADD COLUMN `deadline` TIMESTAMP NUll DEFAULT NULL COMMENT "报名截止时间" after `is_active`
\ No newline at end of file