多列的 SQL 逆透视

Question

我希望以下宽表是非透视的，但仅限于用户对该字段具有真实值以及适当的日期的情况。 当前状态：

---

<头>

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
_______________	_______________________	_______________________	_________________________________________	_________________________________________

必需状态：

---

<头>

Customer_ID	类型	价值	日期
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
_______________________________________________________________________

用于创建表的关联查询和我的尝试不起作用：

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

任何帮助将不胜感激。 TIA

Answer 1

您不能同时拥有多个逆枢轴。相反，您可以根据您的要求使用 Cross Apply 或 Inner join 或 union、union all 或类型的连接。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

取消旋转多个列时，CROSS APPLY (VALUES 通常是最简单、最有效的解决方案。

它为上一个表的每一行创建一个虚拟表，因此将其取消旋转为单独的行。

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;