行列转换之——多行转多列，多列转多行实践版

行列转换之——多行转多列，多列转多行实践版

参考：深入行列转换----多行转多列，多行的计算

参考：sql server动态行列转换

1、多列转行（核心思想，利用row_number() over() 来构造列传行之后的唯一列，来行转列）

 　　要求：

　　　

 实操演示：

select 'a' as 'a','b' as 'b','c' as 'c'
into #temp1
union all
select 'aa','bb','cc'
union all 
select 'aaa','bbb','ccc'

select * from 
(
    select column1,value,row_number() over(partition by column1 order by value) as rn from #temp1
    unpivot(value for column1 in(a,b,c) ) t
) a
pivot(max(value) for rn in ([1],[2],[3])) t1

2、行转多列（核心row_number()）

select 'a' as 'a','b' as 'b','c' as 'c'
into #temp2
union all
select 'a' as 'a','b1' as 'b','c1' as 'c'
union all
select 'aa','bb','cc'
union all 
select 'aa','bb1','cc1'
union all
select 'aaa','bbb','ccc'
select * from #temp2
--1.全表
select * from #temp2
--2.构造row_number()
    select *,row_number() over(partition by a order by a) as 'rn' from  #temp2
--3.行转列
select a, max(case when rn = 1 then A else null end) [B_1],max(case when rn = 1 then B else null end) [C_1],
max(case when rn = 2 then A else null end) [B_2],max(case when rn = 2 then B else null end) [C_2]
from 
(
    select *,row_number() over(partition by a order by a) as 'rn' from  #temp2
) a
GROUP BY A

3.直接行转列

　　

select 'a' as [c1],1 as 'c2'
union all
select 'b' as [c1],2 as 'c2'

;with temp1 as (
select 'a' as [c1],1 as 'c2'
union all
select 'b' as [c1],2 as 'c2'
)
select 
max(case when rn=1 then c1 else null end) as [c1_1],
max(case when rn=1 then c2 else null end) as [c2_1],
max(case when rn=2 then c1 else null end) as [c1_1],
max(case when rn=2 then c2 else null end) as [c2_1]
from 
(select *,row_number() over(order by c1) as [rn] from temp1) t