sql 先进先出 库存

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=110
select * from t


--drop table t
--drop proc wsp

/*

(4 行受影响)
id          name                                               j           c           jdate
----------- -------------------------------------------------- ----------- ----------- -----------------------
1           A                                                  100         100         2007-12-01 00:00:00.000
2           A                                                  200         200         2008-01-07 00:00:00.000
3           B                                                  320         0           2007-12-21 00:00:00.000
4           A                                                  100         30          2008-01-15 00:00:00.000
5           B                                                  90          0           2008-02-03 00:00:00.000
6           A                                                  460         0           2008-02-01 00:00:00.000
7           A                                                  510         0           2008-03-01 00:00:00.000

(7 行受影响)
*/















CREATE TABLE #tmp
  ( ID int IDENTITY (1, 1), 
  单价 decimal(18, 2) NOT NULL , 
  进库数量 decimal(18, 0) NOT NULL , 
  已出数量 decimal(18, 0) NOT NULL
  )
  insert into #tmp(单价,进库数量,已出数量) values(1.1,50,0)
  insert into #tmp(单价,进库数量,已出数量) values(1.3,30,0)
  insert into #tmp(单价,进库数量,已出数量) values(1.4,60,0)
  insert into #tmp(单价,进库数量,已出数量) values(1.5,20,0)
 
     
  select * from #tmp 
  
  
  declare @t decimal(18, 0) --一次出库数量
,@temp decimal(18, 0) --某一单价的临时出库数量
  select @t=20
  update #tmp set @temp=
  case when @t>进库数量-已出数量
  then 进库数量-已出数量 --当出库数量大于某一单价的结存数量时，那么此单价的出库数量就是结存数量，也就是说此单价的库存数量全部消耗完。
  else @t --出库数量小于或等于某一单价的结存数量时，那么此次的出库数量就是实际的出库数量
  end,
   @t=@t-@temp,--减去一次针对某个单价的临时出库数量
   已出数量=@temp+已出数量 --新出库的数量+以前出库的数量
   where 已出数量<>进库数量 --某个单价出库完了就不参于出库计算，即结存数为零的就排除在外
   select * from #tmp
   
   
set @t=40
   update #tmp set @temp=
   case when @t>进库数量-已出数量
   then 进库数量-已出数量
   else @t
   end,
   @t=@t-@temp,
   已出数量=@temp+已出数量
   where 已出数量<>进库数量
  
   select * from #tmp
  
   go
   drop table #tmp