原文:在论坛中出现的比较难的sql问题：39(动态行转列 动态日期列问题)
最近，在论坛中，遇到了不少比较难的sql问题，虽然自己都能解决，但发现过几天后，就记不起来了，也忘记解决的方法了。
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。
求一SQL语句。
http://bbs.csdn.net/topics/390496661
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create table #tab
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(
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col1 char(10),
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col2 char(10),
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item char(10),
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num int,
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[Date] varchar(10))
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insert #tab values('AAA','BBB','A',50,'2013-06-10')
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insert #tab values('ABB','BGG','B',30,'2013-06-10')
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insert #tab values('AAA','BBB','C',80,'2013-06-13')
我的解法：
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create table tab
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(
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col1 char(10),
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col2 char(10),
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item char(10),
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num int,
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[Date] varchar(10)
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)
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insert tab values('AAA','BBB','A',50,'2013-06-10')
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insert tab values('ABB','BGG','B',30,'2013-06-10')
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insert tab values('AAA','BBB','C',80,'2013-06-13')
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--动态生成sql语句
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declare @start_date varchar(10) = '2013-06-01',
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@end_date varchar(10) = '2013-06-30';
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declare @date varchar(10),
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@sql varchar(max) = '',
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@sql1 varchar(8000),
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@sql2 varchar(8000);
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set @date = @start_date;
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set @sql1 = 'select case when rownum = 1 then col1 else '''' end as col1,
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case when rownum = 1 then col2 else '''' end as col2,
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item'
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set @sql2 = 'select col1,col2,item,row_number() over(partition by col1,col2
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order by item) as rownum'
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while @date <= @end_date
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begin
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set @sql1 = @sql1 + ',v_' + REPLACE( right(@date,5),'-','') +
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' as ''' + CAST(DATEPART(month,@date) as varchar) + '/' +
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CAST(DATEPART(day,@date) as varchar) +'''';
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set @sql2 = @sql2 + ',SUM(case when date =''' + @date +
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''' then num else 0 end) as v_' +
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REPLACE( right(@date,5),'-','')
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set @date = CONVERT(varchar(10),dateadd(day,1,@date),120)
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end
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set @sql = @sql1 + ' from (' +
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@sql2 + ' from tab
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group by col1,col2,item' +
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') v'
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--生产的动态sql语句
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select @sql
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exec(@sql)
上面由于是动态生成语句，所以不能用局部的临时表，所以建了一个表。
下面是动态生成的sql语句，经过了格式化：
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select case when rownum = 1 then col1 else '' end as col1,
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case when rownum = 1 then col2 else '' end as col2,
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item,
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v_0601 as '6/1',v_0602 as '6/2',v_0603 as '6/3',
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v_0604 as '6/4',v_0605 as '6/5',
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v_0606 as '6/6',v_0607 as '6/7',
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v_0608 as '6/8',v_0609 as '6/9',
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v_0610 as '6/10',v_0611 as '6/11',
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v_0612 as '6/12',v_0613 as '6/13',
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v_0614 as '6/14',v_0615 as '6/15',
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v_0616 as '6/16',v_0617 as '6/17',
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v_0618 as '6/18',v_0619 as '6/19',
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v_0620 as '6/20',v_0621 as '6/21',
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v_0622 as '6/22',v_0623 as '6/23',
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v_0624 as '6/24',v_0625 as '6/25',
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v_0626 as '6/26',v_0627 as '6/27',
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v_0628 as '6/28',v_0629 as '6/29',
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v_0630 as '6/30'
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from
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(
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select col1,col2,item,
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row_number() over(partition by col1,col2 order by item) as rownum,
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SUM(case when date ='2013-06-01' then num else 0 end) as v_0601,
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SUM(case when date ='2013-06-02' then num else 0 end) as v_0602,
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SUM(case when date ='2013-06-03' then num else 0 end) as v_0603,
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SUM(case when date ='2013-06-04' then num else 0 end) as v_0604,
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SUM(case when date ='2013-06-05' then num else 0 end) as v_0605,
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SUM(case when date ='2013-06-06' then num else 0 end) as v_0606,
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SUM(case when date ='2013-06-07' then num else 0 end) as v_0607,
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SUM(case when date ='2013-06-08' then num else 0 end) as v_0608,
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SUM(case when date ='2013-06-09' then num else 0 end) as v_0609,
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SUM(case when date ='2013-06-10' then num else 0 end) as v_0610,
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SUM(case when date ='2013-06-11' then num else 0 end) as v_0611,
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SUM(case when date ='2013-06-12' then num else 0 end) as v_0612,
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SUM(case when date ='2013-06-13' then num else 0 end) as v_0613,
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SUM(case when date ='2013-06-14' then num else 0 end) as v_0614,
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SUM(case when date ='2013-06-15' then num else 0 end) as v_0615,
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SUM(case when date ='2013-06-16' then num else 0 end) as v_0616,
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SUM(case when date ='2013-06-17' then num else 0 end) as v_0617,
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SUM(case when date ='2013-06-18' then num else 0 end) as v_0618,
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SUM(case when date ='2013-06-19' then num else 0 end) as v_0619,
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SUM(case when date ='2013-06-20' then num else 0 end) as v_0620,
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SUM(case when date ='2013-06-21' then num else 0 end) as v_0621,
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SUM(case when date ='2013-06-22' then num else 0 end) as v_0622,
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SUM(case when date ='2013-06-23' then num else 0 end) as v_0623,
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SUM(case when date ='2013-06-24' then num else 0 end) as v_0624,
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SUM(case when date ='2013-06-25' then num else 0 end) as v_0625,
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SUM(case when date ='2013-06-26' then num else 0 end) as v_0626,
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SUM(case when date ='2013-06-27' then num else 0 end) as v_0627,
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SUM(case when date ='2013-06-28' then num else 0 end) as v_0628,
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SUM(case when date ='2013-06-29' then num else 0 end) as v_0629,
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SUM(case when date ='2013-06-30' then num else 0 end) as v_0630
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from tab
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group by col1,col2,item
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) v