Question

数据库关联查询 有A和B两个表，两个表同过name关联，现在想找出A中有而B中没有的name，怎么用sql语句查询

Answer 1

select a.name from A left join B on A.name=B.name
where B.name is null
或者
select A.name from A where not exists(select * from B where A.name=B.name)

Answer 2

select b.name from a@表 a, b@表 b
where a.name = b.name(+)

Answer 3

select * from A where name not in (select name from B);