从另一列sql / presto计算的百分比

Question

我有这张桌子

month_year  shopid  payment_method   count
Jul-19      3lokpn99    CC           115
Jul-19      3lokpn99    PAYPALL      1
Jul-19      6jyhikmm    CC           180
Jul-19      6jyhikmm    PAYPALL      7
Aug-19      3lokpn99    CC           108
Aug-19      3lokpn99    PAYPALL      4
Aug-19      6jyhikmm    CC           114
Aug-19      6jyhikmm    PAYPALL      3

我正在寻找的是计算当月每种付款方式的百分比。所需的结果是这样的

month_year  shopid  payment_method   count   %
Jul-19      3lokpn99    CC           115    99.14
Jul-19      3lokpn99    PAYPALL      1      0.86
Jul-19      6jyhikmm    CC           180    96.26
Jul-19      6jyhikmm    PAYPALL      7      3.74
Aug-19      3lokpn99    CC           108    96.43
Aug-19      3lokpn99    PAYPALL      4      3.57
Aug-19      6jyhikmm    CC           114    97.4
Aug-19      6jyhikmm    PAYPALL      3      2.56

Answer 1

可能有不同的方法

• 使用窗口功能
• 具有聚合的自我加入（如Wojciech的回答中所述）

窗口函数方法还具有另一个优点，即源数据只能读取一次。

SELECT month_year, shopid, payment_method, count,
    100e0 * count / sum(count) OVER (
        PARTITION BY month_year, shopid
        RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
        AS "%"
FROM ...

（在Presto 318上测试）

请参见Presto窗口功能文档https://prestosql.io/docs/current/functions/window.html

Answer 2

您可以通过查询获得此结果：

SELECT s.*, ROUND(s.count / ss.count_summed * 100,2) AS `%`
FROM stack s
JOIN (SELECT s.month_year, s.shopid, SUM(s.count) AS count_summed FROM stack s GROUP BY s.month_year, s.shopid) ss ON ss.month_year = s.month_year AND ss.shopid = s.shopid;