在SQL Server中連接從表的兩行中獲取單行

Question

我需要使用連接或通過其他方式從表中的兩行中取出單行。我有三個表Account，Account_Perm和User。帳戶表具有一個名爲AccountNum的字段，Account_Perm具有AccountNum，TeamRole和UserName的字段，用戶表具有用戶名。示例數據如下。

• 帳戶==> AccountNum = 1234，5678
• Account_Perm ==> AccountNum = 1234，TeamRole = TeamA; AccountNum = 1234，TeamRole = TeamB
• User ==> TeamRole = TeamA，UserName = John Smith; TeamRole = TeamB，UserName =「凱西布朗」。

我需要使用這些表和我的結果集與列（AccountNum，TeamRole，TeamRole）應該如下。

1234, John Smith, Casey Brown 

通過使用加入，我能得到兩行，1234，約翰·史密斯和1234，凱西·布朗。不過，我需要AccountNum，TeamA的用戶名和TeamB的用戶名單獨記錄。

有人可以幫忙嗎？

查詢：

SELECT 
    A.AccountNum, 
    A.TeamRole, 
    U.Name 
FROM 
    Account A, 
    Account_Perm AA, 
    User U 
WHERE 
    A.AccountNum = AA.AccountNum 
    AND AA.TeamRole IN ('TeamA', 'TeamB') 
    AND AA.UserName = U.Name; 

Answer 1

declare @Account table(AccountNum int); 
insert into @Account values (1234), (5678); 

declare @Account_Perm table (AccountNum int, TeamRole varchar(100)) 
insert into @Account_Perm values(1234, 'TeamA'), (1234, 'TeamB'); 

declare @User table (TeamRole varchar(100), UserName varchar(100)); 
insert into @User values ('TeamA', 'John Smith'), ('TeamB','Casey Brown'); 

--AccountNum, TeamRole, TeamRole) should be as below. 
--1234, John Smith, Casey Brown 
with cte AS 
(
SELECT 
    A.AccountNum, 
    AA.TeamRole, 
    U.UserName 
FROM 
    @Account A join @Account_Perm AA 
     on A.AccountNum = AA.AccountNum 
    join @User U 
     on AA.TeamRole = U.TeamRole 
WHERE AA.TeamRole IN ('TeamA', 'TeamB') 
) 

select * 
from cte pivot(max(UserName) for TeamRole in ([TeamA], [TeamB]))p