求一条数据替换的查询语

[lancelang]

有表A和表B，两个表的字段一样，如果更改了表B中的数据，如何对比两个表查找出那些更改过的记录。
如果有游标的话速度太慢，可不可以不用游标呢？

[LouisXIV]

两种方案，自己选
------------------------------------------------------
declare @a table
(a int,
b int)

declare @b table
(a int,
b int)

insert into @a
select 1,1
union all
select 2,2
union all
select 3,3
union all
select 4,4

insert into @b
select 1,1
union all
select 2,2
union all
select 3,3
union all
select 4,4

select * from @b
select * from @b where checksum(*) not in (select checksum(*) from @a)

update @b
set b=5
where a=4
select * from @b
select * from @b where checksum(*) not in (select checksum(*) from @a)

---------------------------------------------------------------------

declare @a table
(a int,
b int)

declare @b table
(a int,
b int)

insert into @a
select 1,1
union all
select 2,2
union all
select 3,3
union all
select 4,4

insert into @b
select 1,1
union all
select 2,2
union all
select 3,3
union all
select 4,4

select * from @b
select * from @b where checksum(*) not in (select checksum(*) from @a)
select * from @b b where not exists (select a,b from @a where a=b.a and b=b.b)
update @b
set b=5
where a=4
select * from @b
select * from @b where checksum(*) not in (select checksum(*) from @a)
select * from @b b where not exists (select a,b from @a where a=b.a and b=b.b)

[lancelang]

谢谢 LouisXIV(夜游神)
我自己已经搞定了，和你的方法差不多，：）