sql - 如何创建数据成为列

Question

我们如何针对这种情况编写SQL查询？
该表的结构为；

|房间黑色|数据|
| 1 | A | 12 |
| 2 | A | 13 |
| 1 | B | 14 |
| 3 | B | 15 |


预期产量：


|房间A | B |
| 1 | 12 | 14 |
| 2 | 13 |空|
| 3 | null | 15 |

Answer 1

您可以尝试使用条件聚合

DEMO

select room, max(case when BLOK='A' then DATA end) as A,
max(case when BLOK='B' then DATA end) as B
from tablename
group by room

或尝试使用PIVOT

select room,pv.* from 
tablename
pivot(max(DATA) for BLOK in ([A],[B])) pv

输出：

Room    A   B
1      12   14
2      13   
3           15

对于动态数据透视

declare @sql varchar(max)='',@col_list varchar(8000)=''

set @col_list = (select distinct quotename([BLOK])+',' from tablename
for xml path(''))

set @col_list = left (@col_list,len(@col_list)-1)

set @sql = 'select Room,'+@col_list+' from
tablename
pivot (max([DATA]) for [BLOK] in ('+@col_list+'))pv'

exec(@sql)

FIDDLE FOR DYNAMIC PIVOT