sql - 如何使用 case 语句将多个值放入一列中？

Question

我正在尝试将此表中的数据添加到现有查询中:

我想创建一个名为“Assertions”的列，并且只想提取值为“Y”的列名称。例如，对于 Control_ID 13009(第一行)，新的断言列将显示:

Control_ID    Assertions
13009        'Rights_Obligation, Valuation_Allocation, Existence_Occurence'

我尝试使用如下所示的 case when 语句:

case when ca.PRESENTATION_DISCLOSURE = 'Y' then 'Presentation_Disclosure'
when ca.RIGHTS_OBLIGATION = 'Y' then 'Rights_Obligation'
when ca.VALUATION_ALLOCATION = 'Y' then 'Valuation_Allocation'
when ca.COMPLETENESS = 'Y' then 'Completeness'
when ca.EXISTENCE_OCCURRENCE = 'Y' then 'Existence_Occurence'
end as Assertions

此查询不起作用，因为它只是将带有“Y”值的第一个断言放入列中。如何修改查询以使其包含值为“Y”的所有断言？

Answer 1

您可以按如下方式使用CONCAT:

TRIM( ',' FROM 
    CONCAT(CASE when ca.PRESENTATION_DISCLOSURE = 'Y' then 'Presentation_Disclosure' END,
           CASE when ca.RIGHTS_OBLIGATION = 'Y' then ',Rights_Obligation' END,
           CASE when ca.VALUATION_ALLOCATION = 'Y' then ',Valuation_Allocation' END,
           CASE when ca.COMPLETENESS = 'Y' then ',Completeness' END,
           CASE when ca.EXISTENCE_OCCURRENCE = 'Y' then ',Existence_Occurence' END
          )
     ) as Assertions

在 2014 年，您可以使用以下查询，因为 TRIM 在 2014 年不可用。

Stuff( 
    CONCAT(CASE when ca.PRESENTATION_DISCLOSURE = 'Y' then 'Presentation_Disclosure' END,
           CASE when ca.RIGHTS_OBLIGATION = 'Y' then ',Rights_Obligation' END,
           CASE when ca.VALUATION_ALLOCATION = 'Y' then ',Valuation_Allocation' END,
           CASE when ca.COMPLETENESS = 'Y' then ',Completeness' END,
           CASE when ca.EXISTENCE_OCCURRENCE = 'Y' then ',Existence_Occurence' END
          )
     1, 1, '') as Assertions