在查询中查询？ （MS 访问）

Question

例如，我有一个任务表：

TaskTitle DueDate Person Manager
Report     3/28/15  John   Dave
Inspection 4/10/15  Brian  Shane

还有一个联系人表：

ID   Contact  Email                Manager
1    John     john@company.com     False
2    Dave     dave@company.com     True
3    Brian    brian@company.com    False
4    Shane    shane@company.com    True

而我想做的是写一个这样的查询：

PEmail            MEmail             TaskTitle 
john@company.com  Dave@company.com   Report
brian@company.com Shane@company.com  Inspection

我可以得到查询以选择PEmail或MEmail，但不能同时选择？

SELECT [Contacts].[Email], [Tasks].[TaskTitle]
FROM tasks
LEFT JOIN [Contacts] 
ON [Tasks].[Person] = [Contacts].[Contact]

和

SELECT [Contacts].[Email], [Tasks].[TaskTitle]
FROM tasks
LEFT JOIN [Contacts] 
ON [tasks].[Manager] = [Contacts].[Contact]

这有什么特定的名称吗？多重连接还是多重选择？我真的被困在这上面了。

Answer 1

SELECT [ManagerContacts].[Email] MEmail, 
       [PersonContacts].[Email] PEmail, 
       [Tasks].[TaskTitle]
FROM tasks
    LEFT JOIN [Contacts] ManagerContacts
ON [tasks].[Manager] = [ManagerContacts].[Contact]
    LEFT JOIN [Contacts] PersonContacts
ON [tasks].[Person] = [PersonContacts].[Contact]