mysql中You can't specify target table <tbl> for update in FROM clause错误

mysql中You can't specify target table <tbl> for update in FROM clause错误的意思是说，不能先select出同一表中的某些值，再update这个表(在同一语句中)。 例如下面这个sql：

update B set end_time =
(select start_time from B where id ="7777777jjjjjj") where id ="7777777jjjjjj"

这样写：

　　

update B set end_time =
(select A.start_time from
(select start_time from B where id ="7777777jjjjjj")as A

)

 where id ="7777777jjjjjj"