想以表b的某个条件查询表a数据
A
id name userid class
B
id userid chengji
与B的chengji为条件查询 A 的数据
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chengji int 型:
select A.* from A,B where A.userid=B.userid and chengji=XXXX
chengji varchar 型:
select A.* from A,B where A.userid=B.userid and chengji= 'XXXX '
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up
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1楼正解