我有一个任务表，例如：
TaskTitle DueDate Person Manager
Report 3/28/15 John Dave
Inspection 4/10/15 Brian Shane
和联系人表：
ID Contact Email Manager
1 John [email protected] False
2 Dave [email protected] True
3 Brian [email protected] False
4 Shane [email protected] True
我想做的是编写一个查询，像这样：
PEmail MEmail TaskTitle
[email protected] [email protected] Report
[email protected] [email protected] Inspection
我可以查询选择PEmail或MEmail，但不能同时选择两者？
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]
这有什么特别的东西吗？多重联接还是多重选择？我真的一直坚持下去。
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]
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我来说两句