SQL：从不同子查询中的多个 JOINS 中选择

我有两个表Employees和Assignments与内容如下面（分别输出A和B）的图像中可见。每个员工Employees都有最大。1 个项目负责人 ( Assignment.A_Leader = 1) 和最多 1 个项目控制员 ( Assignment.A_Controller = 1) 分配。我想得到一个所有员工的名单，他们是领导或控制者的项目。如果没有为员工分配此类任务，NULL则应出现。我设法列出领导或项目分配。但是，我无法按照此处的建议将两者放在正确的列表中（参见尝试 E）。为了获得所需的决赛桌，我必须添加什么？

以下代码的字母 AE 对应于图像中输出的字母 AE。

我正在使用 Microsoft SQL Server 2017。

-- A: all employees
SELECT * FROM Employee

-- B: all assignments
SELECT * FROM Assignment

-- C: employees with their projects as LEADERS
SELECT E.E_FirstName as First, E.E_LastName as Last, L.A_ProjectID as Leader
FROM Employee E LEFT JOIN
(SELECT A.E_ID, A_ProjectID FROM Assignment A WHERE A.A_Leader=1) L
ON E.E_ID = L.E_ID

-- D: employees with their projects as CONTROLLERS
SELECT E.E_FirstName as First, E.E_LastName as Last, C.A_ProjectID as Controller
FROM Employee E LEFT JOIN
(SELECT A.E_ID, A_ProjectID FROM Assignment A WHERE A.A_Controller=1) C
ON E.E_ID = C.E_ID

-- E: employees with their projects as LEADERS or CONTROLLERS
SELECT X.First, X.Last, X.Leader, Y.Controller FROM
(SELECT E.E_FirstName as First, E.E_LastName as Last, L.A_ProjectID as Leader
FROM Employee E LEFT JOIN
(SELECT A.E_ID, A_ProjectID FROM Assignment A WHERE A.A_Leader=1) L
ON E.E_ID = L.E_ID) as X,
(SELECT E.E_FirstName as First, E.E_LastName as Last, C.A_ProjectID as Controller
FROM Employee E LEFT JOIN
(SELECT A.E_ID, A_ProjectID FROM Assignment A WHERE A.A_Controller=1) C
ON E.E_ID = C.E_ID) as Y