如何在联接查询中显示映射到第二个表中同一列的两列

select a.name Sender, b.name Receiver
FROM t2
INNER JOIN t1 a
ON t2.SenderID = a.ID
INNER JOIN t1 b
ON t2.Receiver = b.ID

将为您提供:

SenderID ReceiverID
Sender1 Receiver1
Sender1 Receiver2
Sender2 Receiver1

如果要在Sender1上对这些结果进行分组,并将接收方名称放在一列中(用空格或其他分隔符分隔),请在上使用group by a.name . 例如在MySQL中,有一个 group_concat 对于 b.name 的。

select a.name Sender, GROUP_CONCAT(b.name SEPARATOR ' ') Receiver
FROM t2
INNER JOIN t1 a
ON t2.SenderID = a.ID
INNER JOIN t1 b
ON t2.Receiver = b.ID
GROUP BY a.name

只需在T1上连接两次:

SELECT TS.[Name] AS SenderName, TR.[Name] AS ReceiverName
FROM T2
    INNER JOIN T1 TS ON TS.ID = T2.SenderID
    INNER JOIN T1 TR ON TR.ID = T2.ReceiverID
ORDER BY TS.[Name], TR.[Name]