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select * from A where cc in (select cc from B)
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select * from A where exists(select cc from B where
cc=A.cc)
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select * from B where cc in (select cc from A)
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select * from B where exists(select cc from A where
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not in ºÍnot exists
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select name from student where name in
('zhang','wang','li','zhao');
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select name from student where name='zhang' or
name='li' or name='wang' or name='zhao'
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