获取两个字段值的唯一组合 [英] Fetch unique combinations of two field values

问题描述

可能以前有人问过，但我找不到答案.

Probably it has been asked before but I cannot find an answer.

表数据有两列:

Source   Dest
1         2
1         2
2         1
3         1

我试图提出一个MS Access 2003 SQL查询，该查询将返回:

I trying to come up with a MS Access 2003 SQL query that will return:

1       2
3       1

但都无济于事.请帮忙！

But all to no avail. Please help!

更新:确切地说，我正在尝试排除2,1，因为已经包含1,2.我只需要顺序无关紧要的唯一组合.

UPDATE: exactly, I'm trying to exclude 2,1 because 1,2 already included. I need only unique combinations where sequence doesn't matter.

推荐答案

对于Ms Access，您可以尝试

For Ms Access you can try

SELECT  DISTINCT
        *
FROM Table1 tM
WHERE NOT EXISTS(SELECT 1 FROM Table1 t WHERE tM.Source = t.Dest AND tM.Dest = t.Source AND tm.Source > t.Source)

表数据示例，这是相同的...

Example with table Data, which is the same...

SELECT  DISTINCT
        *
FROM Data  tM
WHERE NOT EXISTS(SELECT 1 FROM Data t WHERE tM.Source = t.Dest AND tM.Dest = t.Source AND tm.Source > t.Source)

或(格式和访问权限格式好)

SELECT DISTINCT *
FROM Data AS tM
WHERE (((Exists (SELECT 1 FROM Data t WHERE tM.Source = t.Dest AND tM.Dest = t.Source AND tm.Source > t.Source))=False));

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