嗨，我去了一个具有三个字段的简单数据库：
Customer: Date: Amount:
ACME, 2018-01-01, 37.50
......
并希望在表中汇总每个客户每月的金额。 理想的是：
month: 01,02,03,04,05,06,07,08,09,10,11,12
total: (sum of all sales per month)
acme : (sum of customer sales per month)
etc. ...
我以为这样的交叉表可以解决这个问题，但是任何想法似乎都停留在这里
SELECT *
FROM crosstab('SELECT "Customer", to_char("Date",'MM') as "Month",sum("Amount") as "Sale" FROM Sales where "Date">'2018-01-01' GROUP BY 1,2') as "Month" ("Customer" varchar, "Sale" real);