有一个流水表TF,字段有ID,FirstQuantity,ChangeQuantity,FinalQuantity。ID表示物品,后面几个表示期初数量,变化数量,最终数量。
假设表TF现在是空
有一张变动表TC,字段有ID,Quantity。表示某物品的数量。里面会有重复。内容如下:
ID Quantity
1 10
1 20
1 30
那么当我把TC的数据加入到TF后,TF的内容应该如下
ID FirstQuantity ChangeQuantity FinalQuantity
1 0 10 10
1 10 20 30
1 30 30 60
这个功能,用编程的方法很好解决,就是一个一个循环写入,但是效率太慢了。
那么能不能用一条sql语句就搞定呢?
------解决方案--------------------
create table tc(ID int, Quantity int)
insert into tc
select 1 ,10 union all
select 1 ,20 union all
select 1 ,30
go
;with t
as
(
select *,
ROW_NUMBER() over(partition by id order by @@servername) rownum
from tc
)
select ID,
FirstQuantity,
ChangeQuantity,
FirstQuantity+ChangeQuantity as inalQuantity
from
(
select ID,
case when rownum = 1 then 0
else (select SUM(Quantity) from t t2
where t2.ID = t1.id and t2.rownum < t1.rownum)
end as FirstQuantity,
Quantity as ChangeQuantity
from t t1
)tt
/*
ID FirstQuantity ChangeQuantity inalQuantity
1 0 10 10
1 10 20 30
1 30 30 60
*/