在一列中按多个值分组

Question

我的数据表如下所示：

client   Status
   1       a
   2       b
   3       a
   4       d
   5       d
   6       a
   7       e
   8       b
   9       e
  10       f

假设我想按状态分组，但相反，我希望组状态a,b,d（状态I）作为一个组，e,f（状态II）作为另一组

我希望它最终看起来像这样

status Count
   I      7
  II      3

我该如何编写查询？

Answer 1

您可以运行分组并计入一个语句。

SELECT
  CASE WHEN Status IN ('a', 'b', 'd') THEN 'I' ELSE 'II' END AS Status,
  count(*) as count
FROM Table1
GROUP BY  (CASE WHEN Status IN ('a', 'b', 'd') THEN 'I' ELSE 'II' END)
ORDER BY Status

Result:
Status  count
 I      7
II      3

Answer 2

您只需使用CASE语句即可。

SELECT
  CASE WHEN Status IN ('a', 'b', 'd')
    THEN 'I'
  WHEN Status IN ('e', 'f')
    THEN 'II'
  END AS "Status Group",
  count(*) as Count
FROM Table
GROUP BY 1
ORDER BY 1
;

Answer 3

你可以使用group by case

declare @table table ( client INT, STATUS Varchar(10))
insert into @table
select 1  , 'a' union all
select 2 ,  'b' union all
select 3  , 'a' union all
select 4  , 'd' union all
select 5  , 'd' union all
select 6  , 'a' union all
select 7  , 'e' union all
select 8  , 'b' union all
select 9  , 'e' union all
select 10 , 'f'

查询：

select clientgroup, count(*) Count from
(
select case when status in ( 'a','b','d') then 'I' else 'II' end clientgroup from @table 
) x group by clientgroup