Question

我可以请求您提供多对多的查询帮助吗？

我有一个使用MS Access 2010构建的ACE数据库。它有以下表格。

Flags
flagID      flagName                country
1           Stars and Stripes       USA
2           French Tricolour        France
3           The Yellow and Blue     Sweden
4           Union Jack              UK
5           Jolly Roger             Pirates
6           Trinacria               Sicily

Colours
colourID    colour
1           Red
2           Blue
3           White
4           Black
5           Yellow

Juntion
JID         fkFlags     fkColours
For brevity, I’ll omit the field values from the Junction table.

如果我用

查询表格

SELECT Flags.flagName, Flags.country, Colours.colour
FROM Flags INNER JOIN
                 (Colours INNER JOIN Juntion ON Colours.colourID = Juntion.fkColours)
                 ON Flags.flagID = Juntion.fkFlags
WHERE Flags.flagName = 'Jolly Roger' OR Flags.flagName = 'Stars and Stripes';

我的结果是我所期待的。

flagName            country     colour                                       
Stars and Stripes   USA         Red                         
Stars and Stripes   USA         White                       
Stars and Stripes   USA         Blue                        
Jolly Roger         Pirate      Black                       
Jolly Roger         Pirate      White

同样，如果我用

查询表格

SELECT Flags.flagName, Flags.country, Colours.colour
FROM Flags INNER JOIN (Colours INNER JOIN Juntion ON Colours.colourID =   Juntion.fkColours) 
ON Flags.flagID = Juntion.fkFlags
WHERE Colours.Colour IN ((
                      SELECT C.colour
                      FROM Flags INNER JOIN (Colours C INNER JOIN Juntion ON C.colourID = Juntion.fkColours)
                      ON Flags.flagID = Juntion.fkFlags
                      WHERE (c.Colour = 'White')
                      ))
OR Colours.Colour IN ((
                      SELECT C.colour
                      FROM Flags INNER JOIN (Colours C INNER JOIN Juntion ON C.colourID = Juntion.fkColours)
                      ON Flags.flagID = Juntion.fkFlags
                      WHERE (c.Colour = 'Blue')
                      ))

我的结果是我所期待的。

flagName            country colour
Stars and Stripes   USA     White                       
Stars and Stripes   USA     Blue                        
The Yellow and Blue Sweden  Blue                        
Jolly Roger         Pirate  White                       
French Tricolor     France  Blue                        
French Tricolor     France  White                       
Union Jack          UK      White                       
Union Jack          UK      Blue

然而，我真正想要的是获得所有flagNames的结果，其中color = Red，White和Blue。

Stars and Stripes
French Tricolour
Union Jack

另外，鉴于'星条旗'和'Jolly Roger'的旗帜，他们分享了什么颜色？

White

在上面的最后一个查询示例中，如果我将OR更改为AND，则根本不会返回任何结果。我可以请你帮忙写这些问题吗？

感谢您的时间。

Answer 1

对于具有所有三种颜色的标志：

SELECT flagName
FROM Flags
WHERE
    flagID IN
            (
                SELECT Juntion.fkFlags
                FROM Juntion INNER JOIN Colours ON Juntion.fkColours = Colours.colourID
                WHERE Colours.colour = "Red"
            )
        AND flagID IN
                (
                    SELECT Juntion.fkFlags
                    FROM Juntion INNER JOIN Colours ON Juntion.fkColours = Colours.colourID
                    WHERE Colours.colour = "White"
                )
        AND flagID IN
                (
                    SELECT Juntion.fkFlags
                    FROM Juntion INNER JOIN Colours ON Juntion.fkColours = Colours.colourID
                    WHERE Colours.colour = "Blue"
                )

同样，对于两个标志之间的常见颜色

SELECT colour
FROM Colours
WHERE
    colourID IN
            (
                SELECT Juntion.fkColours
                FROM Juntion INNER JOIN Flags ON Juntion.fkFlags = Flags.flagID
                WHERE Flags.flagName = "Stars and Stripes"
            )
        AND colourID IN
                (
                    SELECT Juntion.fkColours
                    FROM Juntion INNER JOIN Flags ON Juntion.fkFlags = Flags.flagID
                    WHERE Flags.flagName = "Jolly Roger"
                )

列出从Many到Many表的常用值

1 个答案: