原文:在论坛中出现的比较难的sql问题：40(子查询 销售和历史库存)
所以，觉得有必要记录下来，这样以后再次碰到这类问题，也能从中获取解答的思路。
求教：我有个表有入库时间，有出库时间，我想得到该样式号每月的销售和历史库存
http://bbs.csdn.net/topics/390629790
库结构大概是这样：
货号 样式号 入库时间 出库时间
a001 10 2011-1-10
b002 10 2011-1-10 2011-2-1
c003 10 2012-1-15 2012-2-2
d004 10 2013-2-3 2013-1-5
e005 10 2013-2-3
f006 15 2011-2-15 2011-3-16
g007 15 2011-2-16 2012-3-16
h009 15 2013-1-10
m012 18 2011-1-4
c009 18 2011-4-5 2012-5-6
f008 18 2012-2-19 2013-1-1
e008 18 2013-1-5 2013-2-6
我想得到的结果：
样式号 日期 销售件数 库存件数
10 2011-2 1 1
10 2012-2 1 1
10 2013-1 1 2
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
我的解法：
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if object_id('tb') is not null
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drop table tb
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go
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create table tb
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(
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[货号] varchar(20),[样式号] int,
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[入库时间] datetime,
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[出库时间] datetime
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)
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insert into tb
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SELECT 'a001',10,'2011-01-10',null UNION ALL
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SELECT 'b002',10,'2011-01-10','2011-02-01' UNION ALL
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SELECT 'c003',10,'2012-01-15','2012-02-02' UNION ALL
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SELECT 'd004',10,'2013-01-03','2013-01-05' UNION ALL
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SELECT 'e005',10,'2013-01-03',null UNION ALL
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SELECT 'f006',15,'2011-02-15','2011-03-16' UNION ALL
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SELECT 'g007',15,'2011-02-16','2012-03-16' UNION ALL
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SELECT 'h009',15,'2013-01-10',null UNION ALL
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SELECT 'm012',18,'2011-01-04',null UNION ALL
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SELECT 'c009',18,'2011-04-05','2012-05-06' UNION ALL
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SELECT 'f008',18,'2012-02-19','2013-01-01' UNION ALL
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SELECT 'e008',18,'2013-01-05','2013-02-06'
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go
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-
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;with t
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as(
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select *,
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row_number() over(partition by 样式号
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order by 入库时间,出库时间) as rownum
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from tb
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),
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tt
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as
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(
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select *,
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case when 出库时间 is null
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then (select top 1 出库时间
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from t t2
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where t1.样式号 = t2.样式号 and
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t1.rownum > t2.rownum
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order by t2.rownum desc)
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else 出库时间
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end as prior_row,
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case when 出库时间 is null
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then (select top 1 出库时间
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from t t2
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where t1.样式号 = t2.样式号 and
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t1.rownum < t2.rownum
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order by t2.rownum )
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else 出库时间
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end as next_row
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from t t1
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),
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ttt
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as
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(
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select 样式号,
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convert(varchar(7),isnull(next_row,prior_row),120) as 日期,
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count(出库时间) 销售件数,
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count(入库时间) 库存件数,
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count(入库时间) - count(出库时间) 剩余库存
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--row_number() over(partition by 样式号
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--order by convert(varchar(7),isnull(next_row,prior_row),120)) as rownum
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from tt
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group by 样式号,
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convert(varchar(7),isnull(next_row,prior_row),120)
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)
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select t1.样式号,t1.日期,
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isnull(t1.销售件数,0) as 销售件数 ,
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isnull(t1.库存件数,0) +
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isnull((select sum(库存件数)-sum(销售件数) as 剩余库存 from ttt t2
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where t2.样式号 = t1.样式号
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and t2.日期 < t1.日期
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),0) -
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isnull(t1.销售件数,0) as 库存件数
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from ttt t1
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order by t1.样式号
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/*
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样式号 日期 销售件数 库存件数
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10 2011-02 1 1
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10 2012-02 1 1
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10 2013-01 1 2
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15 2011-03 1 0
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15 2012-03 1 1
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18 2012-05 1 1
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18 2013-01 1 1
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18 2013-02 1 1
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*/