小编use*_*540的帖子

我正在尝试做类似的事(当然是假的):

SELECT 
  city,
  CASE WHEN COUNT( [group] ) > 1 THEN 'Multiple' ELSE [group] END  AS Type 
FROM 
  offices
GROUP BY
  city

办公室包含以下行:

ID |   group   |  city
----------------------
1  |    'A'    | 'Houston'
2  |    'B'    | 'Houston'
3  |    'C'    | 'Houston'
4  |    'S'    | 'Boston'
5  |    'R'    | 'Detroit'

结果看起来像:

   city   | group
--------------------
 'Houston'| 'Multiple'
 'Boston' |   'S'
 'Detroit'|   'R'

我知道你可以这样做:

SELECT 
  City,
  CASE WHEN COUNT([group]) > 1 THEN 
      'Multiple'
  ELSE 
       ( SELECT [group] …