Mysql 使用两个不同的内部联接列选择colmun的名称和值'；价值观

我不确定MySQL是否能够做这样的事情。我无论如何都不是MySQL大师，但对我来说，这似乎是一个透视表的例子

我看过其他透视表示例，我发现它们充其量也令人困惑，我仍然不确定它是否与我的情况相关

以下是有关数据和表格的示例： Foo表： Foo_元表： 下面是我正在使用的select的一个示例，但并不完全是我想要的： 选择： 下面是我试图选择的表格示例： 选择：

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是的，您正在旋转foo_元字段-至少Oracle的某些版本会这样做，我很确定MySQL不会这样做

通常，要在MySQL中“伪造”一个枢轴，需要进行多个连接。比如：

SELECT
    t.col_one,
    t.col_two,
    t.col_three,
    mthis.this,
    mthat.that,
    mother.other
FROM
    foo t
INNER JOIN
    (select fooid, MetaValue as This from foo_meta where MetaName = 'This') mthis ON t.RowID = mthis.FooID
INNER JOIN
    (select fooid, MetaValue as That from foo_meta where MetaName = 'That') mthat ON t.RowID = mthat.FooID
INNER JOIN
    (select fooid, MetaValue as Other from foo_meta where MetaName = 'Other') mother ON t.RowID = mother.FooID

根据数据的填充方式，您可能必须使用左外接器

RowID | FooID | MetaName | MetaValue
------|-------|----------|-----------
1     | 1     | This     | 302
2     | 1     | That     | 466
3     | 1     | Other    | 132
4     | 2     | This     | 222
5     | 2     | That     | 87
6     | 2     | Other    | 400
7     | 3     | This     | 732
8     | 3     | That     | 55
9     | 3     | Other    | 690

SELECT
    t.col_one,
    t.col_two,
    t.col_three,
    m.MetaName,
    m.MetaValue
FROM
    foo t
INNER JOIN
    foo_meta m ON t.RowID = m.FooID

RowID | col_one | col_two | col_three | This | That | Other
------|---------|---------|---------------------------------
1     | 2       | 34      | 64        | 302  | 466  | 132
2     | 6       | 53      | 23        | 222  | 87   | 400
3     | 8       | 22      | 45        | 732  | 55   | 690

SELECT
    t.col_one,
    t.col_two,
    t.col_three,
    mthis.this,
    mthat.that,
    mother.other
FROM
    foo t
INNER JOIN
    (select fooid, MetaValue as This from foo_meta where MetaName = 'This') mthis ON t.RowID = mthis.FooID
INNER JOIN
    (select fooid, MetaValue as That from foo_meta where MetaName = 'That') mthat ON t.RowID = mthat.FooID
INNER JOIN
    (select fooid, MetaValue as Other from foo_meta where MetaName = 'Other') mother ON t.RowID = mother.FooID