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_datebegin    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)endset @sql = @sql1 + ' from (' +                       @sql2 + ' from tab                                  group by col1,col2,item' +                   ') v' --生产的动态sql语句                  select @sqlexec(@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