SQL 中的自定义聚合

Question

我有一个名为行业的表。有6个字段。架构如下。

在这种情况下，我需要执行自定义聚合。数据库中有 22 个区域。需要进行两个自定义聚合：

1. 需要将区域 1-17 合并为一个值为 00 的新区域。
2. 区域 20 和 21 需要改成另一个区域，代码值为 99。

接下来是我对此总体框架的尝试。我假设创建一个新表是完成此操作的最简单方法。底部是预期结果的一个非常简短的示例。

 create table industry2
 (
 year char(4),
 qtr char(2),
 area char(6),
 industry char(3),
 ownership char(2),
 employment numeric(8,0)
 );

 INSERT INTO Industry2
 (year, qtr, area, industry, ownership, employment)
 SELECT year, qtr, area, (select sum (employment) from dbo.industry where area 
 = '01' or area = '02' and so on):

 2017    01    01   123000    1    456
 2017    01    02   123000    1    101
 2017    01    03   123000    1    103
 2017    01    01   134000    1      6
 2017    01    02   134000    1      7
 2017    01    03   134000    1     12
 2017    01    09   134000    1      1
 2017    01    01   144000    1     14
 2017    01    20   134000    1      7
 2017    01    21   134000    1      8

预期结果

 2017   01     00   123000    1    660
 2017   01     00   134000    1     26
 2017   01     00   144000    1     14
 2017   01     99   134000    1     15

Answer 1

您可以使用CASE WHEN 语句定义您的自定义GROUP BY 子句：

select  [year], 
        [qtr],
        case when [area] in('20','21') then '99' when [area] between 1 and 17 then '00' end as [area], 
        [industry], 
        [ownership], 
        sum([employment]) as [employment_sum] 
from industry2 
group by  
    [year], 
    [qtr], 
    case when [area] in('20','21') then '99' when [area] between 1 and 17 then '00' end, 
    [industry], 
    [ownership] 

结果：