求救A表与B表有相同的字段aa bb，求B表中不存在于A表中的纪录

求救A表与B表有相同的字段aa bb，求B表中不存在于A表中的纪录

select * from b
where aa+bb not in ( select aa+bb from a);

select * from B a
   where not exists (select * from A
         where aa = a.aa and bb = a.bb)