带字符串的 SQL 透视图

Question

我在 SQL Server 中有两个表：Customer 和 Address

客户表：

CustomerID  FirstName  LastName
----------- ---------- ----------
1           Andrew     Jackson         
2           George     Washington

地址表：

AddressID   CustomerID  AddressType City
----------- ----------- ----------- ----------
1           1           Home        Waxhaw     
2           1           Office      Nashville    
3           2           Home        Philadelphia

这是我需要的输出：

CustomerID  Firstname  HomeCity      OfficeCity
----------- ---------- ----------    ----------
1           Andrew     Waxhaw        Nashville
2           George     Philadelphia  Null

这是我的查询，但没有得到正确的结果：

SELECT CustomerID, Firstname, HOme as HomeCity, Office as OfficeCity FROM 
   (SELECT C.CustomerID, C.FirstName, A.AddressID, A.AddressType, A.City 
    FROM Customer C, Address A 
    WHERE C.CustomerID = A.CustomerID)as P
PIVOT (MAX(city) FOR AddressType in ([Home],[Office])) as  PVT

这是我得到的结果：

CustomerID  Firstname  HomeCity      OfficeCity
----------- ---------- ----------    ----------
1           Andrew     Waxhaw        NULL
1           Andrew     NULL          Nashville
2           George     Philadelphia  Null

如您所见，客户 1 在最终结果中出现了两次。是否有可能每个客户只能获得一行？

我查了这个例子，但没有帮助：http://stackoverflow.com/questions/6267660/sql-query-to-convert-rows-into-columns

谢谢

Answer 1

之所以给出这一行，是因为您在子查询“P”的选择列表中有AddressID。因此，即使您在顶层没有 AddressID 选择这个，PIVOT 函数仍然按它分组。您需要将其更改为：

SELECT  CustomerID, Firstname, Home as HomeCity, Office as OfficeCity 
FROM    (   SELECT C.CustomerID, C.FirstName, A.AddressType, A.City 
            FROM #Customer C, #Address A 
            WHERE C.CustomerID = A.CustomerID
        ) AS P
        PIVOT 
        (   MAX(city) 
            FOR AddressType in ([Home],[Office])
        ) AS  PVT

虽然我倾向于使用显式的INNER JOIN，而不是客户和地址之间的隐式连接。

Answer 2

我会这样写：

SELECT C.CustomerID, C.Firstname,
    Home.City as HomeCity,
    Office.City as OfficeCity
FROM Customer C
    LEFT JOIN Address Home
        on Home.CustomerID = C.CustomerID and Home.AddressType = 'Home'
    LEFT JOIN Address Office
        on Office.CustomerID = C.CustomerID and Office.AddressType = 'Office'