sql语句 关于空值

[qq_liang]

X：
字段名：A B C
1 a 22
1 33
Y：
字段名：A B D
1 a 44
1 55
——————————————————————
SELECT x.*
FROM X INNER JOIN
Y ON X.A = Y.A AND X.B = Y.B
结果只有一条记录
1 a 22
我希望得到的是，空值也包括的
1 a 22
1 33
————————————
该怎么写

[liangCK]

多个空值的时候呢？

[rucypli]

SELECT x.*
FROM X INNER JOIN
Y ON X.A = Y.A AND X.B = Y.B
union all
select x.*
from X inner join
Y on X.A=Y.a and X.B is null and Y.B is null

[让你望见影子的墙]

--> (让你望见影子的墙)生成测试数据，时间：2009-02-13
 
if not object_id('X') is null
	drop table X
Go
Create table X([A] int,[B] nvarchar(2),[C] int)
Insert X
select 1,N'a',22 union all
select 1,null,33
Go
Select * from X

--> (让你望见影子的墙)生成测试数据，时间：2009-02-13
 
if not object_id('Y') is null
	drop table Y
Go
Create table Y([A] int,[B] nvarchar(2),[D] int)
Insert Y
select 1,N'a',44 union all
select 1,null,55
Go
Select * from Y


select X.* 
from X join Y on x.a=y.a and isnull(x.b,0)=isnull(y.b,0)

1	a	22
1	NULL	33

[Angiehe]

select x.* from x 
inner join y 
on isnull(x.A,0)=isnull(y.A,0) and isnull(x.B,0)=isnull(y.B,0)