這樣寫和視頻中的寫法 效率上有差別嗎
update user1 as a,user2 as b set a.over='齊天大圣'? where a.user_name=b.user_name；
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update user1 as a,user2 as b set a.over='齊天大圣'? where a.user_name=b.user_name；
2015-08-28
舉報
2015-08-28
update user1 set over='xx' where user_name=(select user_name from user2) 這樣會不會好點？