插入查询结果的问题：

[abcd4321]

表A：
id count
1 100
2 200
3 300
4 400
表B：
id out
2 20
4 600
表C：（不是新建表）
id plus negative
2 180 null
4 null 200

查询A.id=B.id的结果，并判断查询结果的A.ount-B.out的数值的正负，若结果为正数则结果写入plus字段，若结果为负数则结果写入negative字段。
如果在表C中还有其他的字段，而生成新的记录的时候暂时不用写入数据，我该怎么做？

[pengdali]

insert c (id,plus,negative) select a.id,case when a.[count]-b.[out]>=0 then a.[count]-b.[out] end,case when a.[count]-b.[out]<0 then b.[out]-a.[count] end from a,b where a.id=b.id

[friendliu]

insert into tableC(id,plus,negative)
select a.id,case when a.count-b.out>=0 then a.count-b.out end,
case a.count-b.count<0 then b.out-a.count end
from a,b where a.id=b.id

[txlicenhe]

insert c (id,plus,negative)
select a.id,(case when a.[count]-b.[out]>=0 then a.[count]-b.[out] end),(case when a.[count]-b.[out]<0 then b.[out]-a.[count] end)
from a join b on a.id = b.id

[yujohny]

insert into tableC(id,plus,negative)
select A.id,case when a.count-b.out>=0 then a.count-b.out end,
case when a.count-b.out>=0 then a.count-b.out end
from A,B where A.id=B.id

[wzh1215]

create table C([id] int,plus int,negative int,other varchar(100))
create table A([id] int,[count] int)
insert into A([id],[count])
values(1,100)
insert into A([id],[count])
values(2,200)
insert into A([id],[count])
values(3,300)
insert into A([id],[count])
values(4,400)
create table B([id] int, out int)
insert into B([id],out)
values(2,20)
insert into B([id],out)
values(4,600)
insert into C([id],plus,negative)
select A.id,(case when (A.[count]-B.out)>0 then (A.[count]-B.out) end),(case when (A.[count]-B.out)<0 then (B.out-A.[count]) end)
from A,B where A.id=B.id
select * from C
结果为：

id plus negative other
----------- ----------- ----------- --------------------
2 180 0 NULL
4 0 200 NULL

(2 row(s) affected)