SQL：将变量值与多列匹配并选择匹配的列名

Question

我想获取匹配电话号码的记录。共有 3 列保存电话号码。工作、家庭和手机。 我正在编写一个查询来检查电话号码是否与 3 列中的任何一个匹配。

declare @phNo nvarchar(15) = 'xxxxxxxxxx'

select HomePhone, cellphone, workphone, * 
from Contact_Table 
where @phNo in (HomePhone, cellphone, workphone)

此查询运行良好，但我还想要与电话号码匹配的列名。如何获取匹配列的名称？

例如，如果电话号码与“homehpone”匹配，则结果集应返回“homephone”

Answer 1

使用APPLY 运算符也是一种选择：

DECLARE @phNo nvarchar(15) = 'xxxxxxxxxx'

SELECT HomePhone, CellPhone, WorkPhone, a.PhoneType 
FROM (VALUES
   ('xxxxxxxxxx', '000-000-000', '000-000-000'),
   ('000-000-000', '000-000-000', '000-000-000'),
   ('000-000-000', 'xxxxxxxxxx', '000-000-000')
) t (HomePhone, CellPhone, WorkPhone)
OUTER APPLY (VALUES
   (t.HomePhone, 'HomePhone'), 
   (t.CellPhone, 'CellPhone'),
   (t.WorkPhone, 'WorkPhone')
) a (Phone, PhoneType) 
WHERE @phNo = a.Phone

结果：

HomePhone	CellPhone	WorkPhone	PhoneType
xxxxxxxxxx	000-000-000	000-000-000	HomePhone
000-000-000	xxxxxxxxxx	000-000-000	CellPhone

Answer 2

这可以通过 CASE 来完成：

DECLARE @phNo NVARCHAR(15) = 'xxxxxxxxxx';

SELECT homephone,cellphone,workphone, *,
       CASE WHEN @phNo = homephone THEN 'homephone'
            WHEN @phNo = cellphone then 'cellphone'
            WHEN @phNo = workphone THEN 'workphone'
            END AS PhoneMatch
FROM Contact_Table
WHERE @phNo IN (HomePhone,cellphone,workphone);