sql server 2005 中：由三张表中的数据得到一张表，该表的某列对应两个表达式怎么办
SELECT dbo.sell_main.sell_id AS 销售单号, dbo.sp.sp_name AS 商品名称, dbo.sell_son.num AS 购买数量, dbo.sp.sp_dj AS 商品单价, dbo.sell_main.yg_id AS 收银员工号, 
  dbo.sell_main.sell_date AS 日期 into #temp
FROM dbo.sell_main INNER JOIN
  dbo.sell_son ON dbo.sell_main.sp_id = dbo.sell_son.sp_id INNER JOIN
  dbo.sp ON dbo.sell_son.sp_id = dbo.sp.sp_id
declare @xf money,@dj money,@num int,@zk int
declare @sql money
begin
SELECT @num=dbo.sell_son.num , @dj=dbo.sp.sp_dj ,@zk=dbo.sell_son.zk  
FROM dbo.sell_main INNER JOIN
  dbo.sell_son ON dbo.sell_main.sp_id = dbo.sell_son.sp_id INNER JOIN
  dbo.sp ON dbo.sell_son.sp_id = dbo.sp.sp_id
select case 
when zk=0 then '@xf=@dj*@num'
when zk>0 then '@xf=@dj*@num*@zk/10'
select @sql='alter table #temp add'+ @xf +'money '

end
exec(@sql)

------解决方案--------------------
try

SQL code

SELECT dbo.sell_main.sell_id AS 销售单号, dbo.sp.sp_name AS 商品名称, dbo.sell_son.num AS 购买数量, dbo.sp.sp_dj AS 商品单价, dbo.sell_main.yg_id AS 收银员工号,  
  dbo.sell_main.sell_date AS 日期,
  case 
    when dbo.sell_son.zk=0 then dbo.sell_son.num*dbo.sp.sp_dj
    when dbo.sell_son.zk>0 then dbo.sell_son.num*dbo.sp.sp_dj*dbo.sell_son.zk/10
  end as xf
into #temp
FROM dbo.sell_main INNER JOIN
  dbo.sell_son ON dbo.sell_main.sp_id = dbo.sell_son.sp_id INNER JOIN
  dbo.sp ON dbo.sell_son.sp_id = dbo.sp.sp_id