期望效果：（我是拿到一对关系去另一表中的一对关系去对比）

select * From Empoylee Where
(Address1,Address2) in
(Select Address1,Address2
From EmpoyleeAdresses
Where Country = 'Canada')以上无法实现


用这种方案也可以实现 不过速度很慢的

select * from 
              (select (zcbm ||','||fwbm) as t from T_FWZC ) tt where t not in

(select (zcbm ||','||fwbm) as c from T_ZC_FC_GX)

解决方案1：用exists判断

select a.* From Empoylee a
Where exists
    (select 'A' from EmpoyleeAdresses b
     Where
        b.Country = 'Canada'
            and a.Address1=b.Address1
            and a.Address2=b.Address2
        )

解决方案2：用inner join内链接

select *
From
Empoylee
inner join EmpoyleeAdresses
on
Empoylee.Address1=EmpoyleeAdresses.Address1
and
Empoylee.Address2=EmpoyleeAdresses.Address2
Where
EmpoyleeAdresses.Country = 'Canada')select * 
from
Empoylee em
inner join EmpoyleeAdresses emA
on
em.Address1=emA.Address1
and
em.Address2=emA.Address2
and
emA.Country = 'Canada'


解决方案3：表关联

select a.*
From 
Empoylee a ,
  (Select
  Address1,Address2 From EmpoyleeAdresses 
  Where
  Country = 'Canada') b
Where
a.Address1=b.Address1
and
a.Address2 = b.Address2



主观感觉方案1更快一些，客观上，还没在查询分析器里用"显示执行计划"看哪种写法效率高些. 

如果是Delete语句，写法如下：

Delete From Empoylee 
Where exists
    (select 'A' from EmpoyleeAdresses b
     Where
        b.Country = 'Canada'
            and Empoylee.Address1=b.Address1
            and Empoylee.Address2=b.Address2
        )
注意Delete from 后的表不能用别名～