sql problem more difficult to appear in the forum: 40 (sub-query historical sales and inventory)

Original: SQL problem more difficult to appear in the forum: 40 (sub-query historical sales and inventory)

Recently, in the forum, I met a lot more difficult sql problem, although they can be resolved, but found a few days later, they can not remember, forget the solution of.

So, I feel the need to be recorded, so that after the encounter this problem again, and get answers from the idea.

Neighborhoods: I have a table has storage time, there is a library time, I want the style number of monthly sales and inventory history

http://bbs.csdn.net/topics/390629790

library structure something like this:
Item No. style timespan leaving time
A001 2011-1-10 10        
B002 10 2011-1-10 2011-2-1
C003 10 2012 2012-2-2 -1-15
D004 10 2013-2-3 2013-1-5
E005 10 2013-2-3        
F006 2011-2-15 2011-3-16 15
G007 15 2012-3 2011-2-16 -16
H009 2013-1-10 15    
M012 18 is 2011-1-4        
C009 18 is 2011-4-5 2012-5-6
F008 18 is 2012-2-19 2013-1-1
E008 18 is 2013-1-5 2013-2 -6
 
I want to get results:
the number of inventory items style No. date sales part    
10 2011-2 1 1
10 2012-2 1 1
10 2 1 2013-1
15    2011-3    1    0
15    2012-3    1    1
18    2012-5    1    1
18    2013-1    1    1
18    2013-2    1    1

My solution:

   
   
if object_id('tb') is not null
drop table tb
go

create table tb
(
[货号] varchar( 20),[样式号] int,
[入库时间] datetime,
[出库时间] datetime
)

insert into tb
SELECT 'a001', 10, '2011-01-10', null UNION ALL
SELECT 'b002', 10, '2011-01-10', '2011-02-01' UNION ALL
SELECT 'c003', 10, '2012-01-15', '2012-02-02' UNION ALL
SELECT 'd004', 10, '2013-01-03', '2013-01-05' UNION ALL
SELECT 'e005', 10, '2013-01-03', null UNION ALL
SELECT 'f006', 15, '2011-02-15', '2011-03-16' UNION ALL
SELECT 'g007', 15, '2011-02-16', '2012-03-16' UNION ALL
SELECT 'h009', 15, '2013-01-10', null UNION ALL
SELECT 'm012', 18, '2011-01-04', null UNION ALL
SELECT 'c009', 18, '2011-04-05', '2012-05-06' UNION ALL
SELECT 'f008', 18, '2012-02-19', '2013-01-01' UNION ALL
SELECT 'e008', 18, '2013-01-05', '2013-02-06'
go


;with t
as(
select *,
row_number() over( partition by 样式号
order by 入库时间,出库时间) as rownum
from tb
),

tt
as
(
select *,
case when 出库时间 is null
then ( select top 1 出库时间
from t t2
where t1.样式号 = t2.样式号 and
t1.rownum > t2.rownum
order by t2.rownum desc)
else 出库时间
end as prior_row,

case when 出库时间 is null
then ( select top 1 出库时间
from t t2
where t1.样式号 = t2.样式号 and
t1.rownum < t2.rownum
order by t2.rownum )
else 出库时间
end as next_row

from t t1
),

ttt
as
(
select 样式号,
convert( varchar( 7), isnull(next_row,prior_row), 120) as 日期,
count(出库时间) 销售件数,
count(入库时间) 库存件数,
count(入库时间) - count(出库时间) 剩余库存
--row_number() over(partition by 样式号
--order by convert(varchar(7),isnull(next_row,prior_row),120)) as rownum
from tt
group by 样式号,
convert( varchar( 7), isnull(next_row,prior_row), 120)

)

select t1.样式号,t1.日期,
isnull(t1.销售件数, 0) as 销售件数 ,

isnull(t1.库存件数, 0) +
isnull(( select sum(库存件数)- sum(销售件数) as 剩余库存 from ttt t2
where t2.样式号 = t1.样式号
and t2.日期 < t1.日期
), 0) -
isnull(t1.销售件数, 0) as 库存件数

from ttt t1
order by t1.样式号
/*
样式号 日期 销售件数 库存件数
10 2011-02 1 1
10 2012-02 1 1
10 2013-01 1 2
15 2011-03 1 0
15 2012-03 1 1
18 2012-05 1 1
18 2013-01 1 1
18 2013-02 1 1
*/