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

create table #tab
(
col1 char(10),
col2 char(10),
item char(10),
num int,
[Date] varchar(10))
insert #tab values('AAA','BBB','A',50,'2013-06-10')
insert #tab values('ABB','BGG','B',30,'2013-06-10')
insert #tab values('AAA','BBB','C',80,'2013-06-13')

我的解法：

create table tab
(
col1 char(10),
col2 char(10),
item char(10),
num int,
[Date] varchar(10)
)

insert tab values('AAA','BBB','A',50,'2013-06-10')
insert tab values('ABB','BGG','B',30,'2013-06-10')
insert tab values('AAA','BBB','C',80,'2013-06-13')

--动态生成sql语句
declare @start_date varchar(10) = '2013-06-01',
@end_date   varchar(10) = '2013-06-30';

declare @date  varchar(10),
@sql   varchar(max) = '',
@sql1  varchar(8000),
@sql2  varchar(8000);

set @date = @start_date;

set @sql1 = 'select case when rownum = 1 then col1 else '''' end as col1,
case when rownum = 1 then col2 else '''' end as col2,
item'

set @sql2 = 'select col1,col2,item,row_number() over(partition by col1,col2
order by item) as rownum'

while @date <= @end_date
begin
set @sql1 = @sql1 + ',v_' + REPLACE( right(@date,5),'-','') +
' as ''' + CAST(DATEPART(month,@date) as varchar) + '/' +
CAST(DATEPART(day,@date) as varchar) +'''';
set @sql2 = @sql2 + ',SUM(case when date =''' + @date +
''' then num else 0 end) as v_' +
REPLACE( right(@date,5),'-','')

set @date = CONVERT(varchar(10),dateadd(day,1,@date),120)
end

set @sql = @sql1 + ' from (' +
@sql2 + ' from tab
group by col1,col2,item' +
') v'

--生产的动态sql语句
select @sql

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：

select case when rownum = 1 then col1 else '' end as col1,
case when rownum = 1 then col2 else '' end as col2,
item,

v_0601 as '6/1',v_0602 as '6/2',v_0603 as '6/3',
v_0604 as '6/4',v_0605 as '6/5',
v_0606 as '6/6',v_0607 as '6/7',
v_0608 as '6/8',v_0609 as '6/9',
v_0610 as '6/10',v_0611 as '6/11',
v_0612 as '6/12',v_0613 as '6/13',
v_0614 as '6/14',v_0615 as '6/15',
v_0616 as '6/16',v_0617 as '6/17',
v_0618 as '6/18',v_0619 as '6/19',
v_0620 as '6/20',v_0621 as '6/21',
v_0622 as '6/22',v_0623 as '6/23',
v_0624 as '6/24',v_0625 as '6/25',
v_0626 as '6/26',v_0627 as '6/27',
v_0628 as '6/28',v_0629 as '6/29',
v_0630 as '6/30'
from
(
select col1,col2,item,

row_number() over(partition by col1,col2  order by item) as rownum,

SUM(case when date ='2013-06-01' then num else 0 end) as v_0601,
SUM(case when date ='2013-06-02' then num else 0 end) as v_0602,
SUM(case when date ='2013-06-03' then num else 0 end) as v_0603,
SUM(case when date ='2013-06-04' then num else 0 end) as v_0604,
SUM(case when date ='2013-06-05' then num else 0 end) as v_0605,
SUM(case when date ='2013-06-06' then num else 0 end) as v_0606,
SUM(case when date ='2013-06-07' then num else 0 end) as v_0607,
SUM(case when date ='2013-06-08' then num else 0 end) as v_0608,
SUM(case when date ='2013-06-09' then num else 0 end) as v_0609,
SUM(case when date ='2013-06-10' then num else 0 end) as v_0610,
SUM(case when date ='2013-06-11' then num else 0 end) as v_0611,
SUM(case when date ='2013-06-12' then num else 0 end) as v_0612,
SUM(case when date ='2013-06-13' then num else 0 end) as v_0613,
SUM(case when date ='2013-06-14' then num else 0 end) as v_0614,
SUM(case when date ='2013-06-15' then num else 0 end) as v_0615,
SUM(case when date ='2013-06-16' then num else 0 end) as v_0616,
SUM(case when date ='2013-06-17' then num else 0 end) as v_0617,
SUM(case when date ='2013-06-18' then num else 0 end) as v_0618,
SUM(case when date ='2013-06-19' then num else 0 end) as v_0619,
SUM(case when date ='2013-06-20' then num else 0 end) as v_0620,
SUM(case when date ='2013-06-21' then num else 0 end) as v_0621,
SUM(case when date ='2013-06-22' then num else 0 end) as v_0622,
SUM(case when date ='2013-06-23' then num else 0 end) as v_0623,
SUM(case when date ='2013-06-24' then num else 0 end) as v_0624,
SUM(case when date ='2013-06-25' then num else 0 end) as v_0625,
SUM(case when date ='2013-06-26' then num else 0 end) as v_0626,
SUM(case when date ='2013-06-27' then num else 0 end) as v_0627,
SUM(case when date ='2013-06-28' then num else 0 end) as v_0628,
SUM(case when date ='2013-06-29' then num else 0 end) as v_0629,
SUM(case when date ='2013-06-30' then num else 0 end) as v_0630
from tab
group by col1,col2,item
) v