无敌铃铃后

update set name = 'xxx' where id = 1 and is_delete = 0 where后面同时用了两个字段id和is_delete,锁表还是锁行?

** 我发现mysql的group by 后面的字段没有严格要求，甚至select后面的字段可以不出现在group by后面**