sql-server - TSQL 合并和分组值

Question

我有这个 sql 结果

color    red     AA
color    red     BB
color    red     CC
color    blue    DD
color    blue    EE

有没有办法按列合并，以获得以下结果？

color    red     AA
                 BB
                 CC
         blue    DD
                 EE

Answer 1

这通常是您在应用程序的表示层上执行的操作，但如果您想在 SQL 中执行此操作，您可以使用row_number()：

select 
  case when col1rn = 1 then col1 else '' end col1,
  case when col2rn = 1 then col2 else '' end col2,
  col3
from
(
  select col1, col2, col3,
    row_number() over(partition by col1 order by col1, col2, col3) col1rn,
    row_number() over(partition by col1, col2 order by col1, col2, col3) col2rn
  from yt
) d;

请参阅SQL Fiddle with Demo。你可以from yt用你的查询替换，给出结果：

|  COL1 | COL2 | COL3 |
-----------------------
| color | blue |   DD |
|       |      |   EE |
|       |  red |   AA |
|       |      |   BB |
|       |      |   CC |
|  test | blue |   CC |
|       |  red |   AA |
|       |      |   BB |

Answer 2

Here we are using a ranking function to find your redundant data, and then a case can blank it out as necessary. Note also that we're handling multiple "categories" or "groups" or whatever you happen to be partitioning by in your real data (shown as columns a and b here).

;with cte as (
    select 'color' as a, 'red' as b, 'AA' as c
    union all select 'color', 'red', 'BB'
    union all select 'color', 'red', 'CC'
    union all select 'color', 'blue', 'DD'
    union all select 'color', 'blue', 'EE'
    union all select 'smell', 'bad', 'AA'
    union all select 'smell', 'bad', 'BB'
    union all select 'smell', 'bad', 'CC'
    union all select 'smell', 'good', 'DD'
    union all select 'smell', 'good', 'EE'
)
select case when row_number() over (partition by a order by b, c) = 1 then a else '' end as ColA
    , case when row_number() over (partition by a, b order by c) = 1 then b else '' end as ColB
    , c as ColC
from cte
order by a, b, c

This will yield the following result:

ColA  ColB ColC
----- ---- ----
color blue DD
           EE
      red  AA
           BB
           CC
smell bad  AA
           BB
           CC
      good DD
           EE