如何使用mysql查找平均值？

Question

我有这样的数据

    +-------------+-------+
    | countryCode | label |
    +-------------+-------+
    | KM          | A     | 
    +-------------+-------+
    | AD          | A     | 
    +-------------+-------+
    | TH          | B     |
    +-------------+-------+
    | KM          | B     |
    +-------------+-------+

如何找到像这样的平均数

    +-------------+-----+-----+-------+
    | countryCode | A   | B   | count |
    +-------------+-----+-----+-------+
    | KM          | 0.5 | 0.5 | 2     |
    +-------------+-----+-----+-------+
    | AD          | 1   | 0   | 1     |
    +-------------+-----+-----+-------+
    | TH          | 0   | 1   | 1     |
    +-------------+-----+-----+-------+

Answer 1

你走了。

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你可以弄清楚其余部分。