SQL SELECT JOIN COLUMN ALIAS

Question

在此先感謝您的幫助：

[People]表有兩列：

• 是PersonID
• PERSONNAME

[Marriages]表有三列：

• MarriageID
• PersonIDa
• PersonIDb

我想選擇以下列：

• MarriageID
• PersonName（適用於personIDa）
• PersonName（for personIDb）

我想我需要使用帶有JOIN的SELECT語句，但我不確定如何為每個PersonName分配一個唯一的別名。 這是我到目前為止（這不起作用）：

SELECT 
    [Marriages].[MarriageID], 
    [People].[PersonName] AS aName, 
    [People].[PersonName] AS bName  
FROM 
    [Marriages]  
JOIN 
    [People] ON [Marriages].[PersonIDa] = [People].[PersonID]  
JOIN 
    [People] ON [Marriages].[PersonIDb] = [People].[PersonID]  

再次感謝...

Answer 1

這符合您要完成的任務嗎？

SELECT m.[MarriageID], peopleA.[PersonName] AS aName, peopleB.[PersonName] AS bName  
FROM [Marriages]  M
JOIN [People] peopleA ON m.[PersonIDa] = peopleA.[PersonID]  
JOIN [People] peopleB ON m.[PersonIDb] = peopleB.[PersonID]  

Answer 2

我想你正試圖這樣做......

SELECT 
m.[MarriageID], 
pa.[PersonName] AS aName,
pb.[PersonName] AS bName  
FROM [Marriages] m
JOIN [People] pa ON m.[PersonIDa] = pa.[PersonID]  
JOIN [People] pb ON m.[PersonIDb] = pb.[PersonID];

Answer 3

你需要這樣的東西：

Select MarriageID, a.PersonName, b.PersonName
From Marriages m
Join People a On a.PersonID = m.Person1ID 
Join People b on b.PersonID = m.Person2ID 

Answer 4

不要忘記你需要什么類型的JOIN ......“INNER JOIN”/“LEFT OUTER JOIN”/“RIGHT OUTER JOIN”/“CROSS JOIN”

SELECT MarriageID, a.PersonName, b.PersonName
FROM Marriages m JOIN People a ON a.PersonID = m.Person1ID 
                 JOIN People b ON b.PersonID = m.Person2ID 

Answer 5

感謝大家; 你的建議完美無缺。 當我試圖在JOIN語句中為重復表創建別名時，我試圖在SELECT語句中為重復列創建別名。

對於遇到此問題的其他人：

SELECT  
[TABLE1 NAME].[TABLE1 COLUMN],  
(TABLE2 ALIAS1).[TABLE2 COLUMN],  
(TABLE2 ALIAS2).[TABLE2 COLUMN],  
FROM [TABLE1 NAME]  
JOIN [TABLE2 NAME] (TABLE2 ALIAS1) ON [TABLE1 NAME].[TABLE1 MATCHING COLUMN] = (TABLE2 ALIAS1).[TABLE2 MATCHING COLUMN]  
JOIN [TABLE2 NAME] (TABLE2 ALIAS2) ON [TABLE1 NAME].[TABLE1 MATCHING COLUMN] = (TABLE2 ALIAS2).[TABLE2 MATCHING COLUMN]  

別名在JOIN語句中創建，並應用於SELECT語句中的使用位置，而不是相反。