Question

提前感谢您的帮助：

[People]表有两列：

PersonID
PersonName

[Marriages]表有三列：

MarriageID
PersonIDa
PersonIDb

我想选择以下列：

MarriageID
PersonName（for personIDa）
PersonName（for personIDb）

我想我需要使用带有SELECT的{{1}}语句，但我不确定如何为每个JOIN分配唯一的别名。这是我到目前为止（这不起作用）：

PersonName

再次感谢...

Answer 1

这是否符合您要完成的任务？

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

我想你正试图这样做......

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

您将需要以下内容：

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

不要忘记你需要什么类型的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

谢谢大家;你的建议完美无缺。当我试图在JOIN语句中为重复表创建别名时，我试图在SELECT语句中为重复列创建别名。

对于遇到此问题的其他人：

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]

别名在JOIN语句中创建，并应用于SELECT语句中的使用位置，而不是相反。

SQL SELECT JOIN COLUMN ALIAS

5 个答案: