求一存储过程,单表(4个字段),救急.在线急等.

[dljinsui]

表A

字段：
客户编码：CustID (字符) [主键]
商品编码：ProID (字符) [主键]
销售日期：saleDate(日期) [主键]
重量： saleTotalweight(decimal,4位小数)


求一存储过程

传入该字段四个参数，
参数顺序为字段顺序(custID,ProID,saleDate,saleTotalweight)

返回值:
累加后的重量

要求：
1.如已存在该条纪录，重量累加：
select saleTotalweight from A where CustID=@CustID and proID=@proID and saleDate = @saleDate

if exist() -> 原有重量+传入重量
if 没有前三个字段（主键）对应纪录，则insert()一条。
insert()时注意，如果是负数，重量为零，正数为传入值。

2.传入的重量可能为负数（冲减）
也是传入重量与原有重量累加，如累加值为负，由update这纪录的重量为零。

[-狙击手-]

create proc procname
@custid varchar(10),
@proid varchar(10),
@saledate datetime,
@saletotalweight decimal(12,4),
@ret decimal(12,4) output
as
declare @old decimal(12,4)
select @old = saleTotalweight from A where CustID=@CustID and proID=@proID and saleDate = @saleDate
if @@rowcount > 1
begin
set @ret = @old + @saletotalweight
if @ret < 0
update a set saleTotalweight = 0
where CustID=@CustID and proID=@proID and saleDate = @saleDate
end
else
insert a select @custid ,@proid ,@saledate,case when @saletotalweight > 0 then @saletotalweight else 0 end



go

[中国风]

if exists(select 1 from A where CustID=@CustID and proID=@proID and saleDate = @saleDate )
update a
set saleTotalweight=saleTotalweight+@saleTotalweight
where CustID=@CustID and proID=@proID and saleDate = @saleDate
else
insert a values(@CustID,@proID,@saleDate,@saleTotalweight)