如何显示列的百分比

Question

我想计算每个 typeItem 相对于所有 typeItem 在每个月的百分比，我该如何实现？

我有一个 table typeItem, AMOUNT, month in followwing

SELECT
    SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) "JAN"
    SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) "FEB"
...
FROM (SELECT AMOUNT, MONTH, ItemTYPE FROM MY TABLE)
GROUP BY typeItem

这给了我

OUTPUT:
ItemType  JAN   FEB  ...

A         123   456
B         234   567
...

--但我想要：

SELECT
    SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) "JAN"
--CALCULATE PERCENTAGE FOR JAN (AMOUNT ItemType/AMOUNT ALL ItemType) "JAN %"
    SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) "FEB"
--CALCULATE PERCENTAGE FOR FEB(AMOUNT ItemType/AMOUNT ALL ItemType) "FEB %"
...
FROM (SELECT PRICE, MONTH, ItemTYPE FROM MY TABLE)
GROUP BY typeItem

OUTPUT:
ItemType  JAN  JAN%        FEB     FEB%  ...

A         123   0.11       456     0.15
B         234   0.13       567     0.16
...

Answer 1

你可以除：

SELECT SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) as "JAN",
       SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) / SUM(SUM(CASE WHEN MONTH = 1 THEN AMOUNT END)) OVER () as "JAN",       
       SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) as "FEB",
       SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) / SUM(SUM(CASE WHEN MONTH = 2 THEN AMOUNT END)) OVER () as "FEB",
       . . .
FROM T
WHERE MONTH IN (1, 2, . . . )
GROUP BY typeItem

Answer 2

您可以使用如下解析函数实现：

SELECT
    SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) AS JAN,
    SUM(CASE WHEN MONTH = 1 THEN AMOUNT END) / MAX(CASE WHEN MONTH = 1 THEN SM END) AS "JAN%",
    SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) AS FEB,
    SUM(CASE WHEN MONTH = 2 THEN AMOUNT END) / MAX(CASE WHEN MONTH = 2 THEN SM END) AS "FEB%"
...
FROM (SELECT AMOUNT, MONTH, ItemTYPE,
SUM(AMOUNT) OVER (PARTITION BY MONTH) AS SM
FROM MY TABLE)
GROUP BY typeItem

注意：当月金额之和为零时，需要处理除以零的情况。

干杯！！

如何显示列的百分比

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