库存先进先出简单例子

--库存先进先出简单例子：

create table t(
id int identity(1,1),
name varchar(50),--商品名称
j int, --入库数量
c int, --出库数量
jdate datetime --入库时间
)
insert into t(name,j,c,jdate) select 'A',100,0,'2007-12-01'
insert into t(name,j,c,jdate) select 'A',200,0,'2008-01-07'
insert into t(name,j,c,jdate) select 'B',320,0,'2007-12-21'
insert into t(name,j,c,jdate) select 'A',100,0,'2008-01-15'
insert into t(name,j,c,jdate) select 'B',90,0,'2008-02-03'
insert into t(name,j,c,jdate) select 'A',460,0,'2008-02-01'
insert into t(name,j,c,jdate) select 'A',510,0,'2008-03-01'
go

create proc wsp
@name varchar(50),--商品名称
@cost int --销售量
as
--先得出该货物的库存是否够
declare @spare float --剩余库存
select @spare=sum(j)-sum(c) from t where name=@name
if(@spare>=@cost)
begin
--根据入库日期采用先进先出原则对货物的库存进行处理
update t set c=
case when (select @cost-isnull(sum(j),0)+isnull(sum(c),0) from t where name=@name and jdate<=a.jdate and j!=c)>=0
then a.j
else
case when (select @cost-isnull(sum(j),0)+isnull(sum(c),0) from t where name=@name and jdate<a.jdate and j!=c)<0 then 0
else (select @cost-isnull(sum(j),0)+isnull(sum(c),0)+a.c from t where name=@name and jdate<a.jdate and j!=c)
end
end
from t a where name=@name and j!=c
end
else
raiserror('库存不足',16,1)
return
go

--测试：

exec wsp @name='A',@cost=180
select * from t

--drop table t
--drop proc wsp