SQL 多列逆轴

Question

我希望将以下宽 table 取消透视，但仅限于用户对该字段具有真实值以及适当日期的情况。当前状态：

CUSTOMER_ID	First_Party_Email	Third_Party_Email	First_Party_Email_Date	Third_Party_Email_Date
40011111	1	1	2021-01-22 04:38:00.000	2021-01-17 06:38:00.000
50022222	NULL	1	NULL	2021-01-18 04:38:00.000
80066666	1	NULL	2021-01-24 05:38:00.000	NULL
_______________	_______________________	_______________________	_______________________________	_______________________________

要求的状态：

Customer_ID	Type	Value	Date
40011111	First_Party_Email	1	22/01/2021 04:38
40011111	Third_Party_Email	1	17/01/2021 06:38
50022222	Third_Party_Email	1	18/01/2021 04:38
80066666	First_Party_Email	1	24/01/2021 05:38
_______________________________________________________________________

创建 table 的关联查询，我的尝试无效：

create table Permissions_Obtained
(Customer_ID bigint
,First_Party_Email  bit
,Third_Party_Email  bit
,First_Party_Email_Date datetime    
,Third_Party_Email_Date datetime
)

insert into Permissions_Obtained
(Customer_ID
,First_Party_Email
,Third_Party_Email
,First_Party_Email_Date
,Third_Party_Email_Date
)
VALUES
(40011111,  1,      1,      '2021-01-22 04:38', '2021-01-17 06:38'),
(50022222,  NULL,   1,      NULL,               '2021-01-18 04:38'),
(80066666,  1,      NULL,   '2021-01-24 05:38', null)

select * 
from Permissions_Obtained

select 
customer_id, Permission
from Permissions_Obtained
unpivot
(
  GivenPermission
  for Permission in (
First_Party_Email, Third_Party_Email
)
) unpiv1, 
unpivot
(
  GivenPermissionDate
  for PermissionDate in (
First_Party_Email_Date, Third_Party_Email_Date
)
) unpiv2
where GivenPermission = 1

--drop table Permissions_Obtained

如有任何帮助，我们将不胜感激。 TIA

Answer 1

您不能同时拥有多个逆轴。相反，您可以根据需要使用交叉应用或内部联接或联合、联合所有或某种联接。我已经使用 join 和 unpivot 为此添加了一个示例答案。

   SELECT 
       unpvt.Customer_ID 
       , [Type]
       ,  ISNULL(po.First_Party_Email ,po.Third_Party_Email) AS [Value] 
       ,CASE WHEN unpvt.Type = 'First_Party_Email' THEN po.First_Party_Email_Date
             ELSE  po.Third_Party_Email_Date  
             END AS  [Date]

     FROM   
        (
         SELECT 
           Customer_ID, First_Party_Email , Third_Party_Email  
           FROM Permissions_Obtained 
         ) p  
       UNPIVOT  
          (  [Value] FOR [Type]     IN   
               (First_Party_Email , Third_Party_Email )  
          )AS unpvt
          INNER JOIN  Permissions_Obtained [po] 
             on [po].Customer_ID = unpvt.Customer_ID

Answer 2

当取消透视多列时，CROSS APPLY (VALUES 通常是最简单和最有效的解决方案。

它为前一个 table 的每行创建一个虚拟的 table，因此将其取消旋转成单独的行。

SELECT
    p.Customer_Id,
    v.[Type],
    v.Value,
    v.Date
FROM Permissions_Obtained p
CROSS APPLY (VALUES
    ('First_Party_Email', p.First_Party_Email, p.First_Party_Email_Date),
    ('Third_Party_Email', p.Third_Party_Email, p.Third_Party_Email_Date)
) v([Type], Value, Date)
where v.Value IS NOT NULL;

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