例如上表(memorystorage表):
每次退柜操作时,要把退柜时间return_time更新(0000-00-00 00:00:00 -> $nowtime)
update memorystorage set return_time = $nowtime' where return_time = ( select A.return_time from
(select return_time from memorystorage where student_id = '25'order by get_time desc limit 1)as A)
要将select出的结果再通过中间表select一遍,这样就规避了错误。注意,这个问题只出现于mysql,mssql和oracle不会出现此问题。
error:You can't specify target table 'memorystorage' for update in FROM clause!!!