语句如下：只能显示存在在另一个表中的记录集；
select b.* from taxlist a, materialbat b
where a.batchno = b.batchno
and a.abroadnum = b.abroadnum
and a.materialno = b.materialno
select a.* from taxlist a
where not exists(select * from materialbat b where
a.batchno = b.batchno
and a.abroadnum = b.abroadnum
and a.materialno = b.materialno
)
