Question

我需要协助构建此查询，我需要从同一个表中选择不同的值但不同的唯一键。

详细说明以下示例：

我有两张桌子：

问题（IssueID，AuthorID_FK，AssigedID_FK，......）
用户（UserID，User_Label，...）

作者ID_FK ＆amp; AssigedID_FK 与表用户相关联，我需要在同一查询结果中获取 User_Label 。

你能帮忙吗？

谢谢，

Answer 1

SELECT a.IssueID, b.User_Label, c.User_Label FROM Issues a
INNER JOIN USERS b on a.AuthorID_FK = b.UserID
INNER JOIN USERS c on a.AssignedID_FK = c.UserID

类似的东西:)这应该在MS SQL Server中运行

Answer 2

嗯，这个也应该有效：）

SELECT IssueID, U.User_Label FROM Issues I
INNER JOIN Users U ON U.UserID = I.AuthorID_FK

UNION

SELECT IssueID, U.User_Label FROM Issues I
INNER JOIN Users U ON U.UserID = I.AssigedID_FK

Answer 3

惯于

SELECT a.IssueID, b.UserID 
FROM Issues a 
    JOIN Users b ON (a.AuthorID_FK=b.UserID OR a.AssignedID_FK = b.UserID)

工作？

Answer 4

你可能想尝试这样的事情

SELECT
    issues.IssueID,
    Authour.User_Label AS Author_Label,
    Assigned.User_Label AS Assigned_user_Label
FROM
    issues
    INNER JOIN users AS Authour ON Authour.UserID = issues.AuthorID_FK
    INNER JOIN users AS Assigned ON Assigned.UserID = issues.AssignedID_FK

SQL查询 - 同一字段上的多个联接

4 个答案: