签到表创建时间字段允许为空

api/src/main/resources/db.sql

@@ -41,5 +41,5 @@ create table sign_record
     uid         int(10)     not null,
     point       int(10)     not null,
     ip          varchar(50) not null,
-    create_time datetime    not null
+    create_time datetime    default current_timestamp
 ) engine = innodb comment '打卡记录表';