Postgresql 博士后按月选择总和
我有证据:Postgresql 博士后按月选择总和,postgresql,select,Postgresql,Select,我有证据: id id_customer id_service amount date 1 1 1 50.0 2018-01-10 2 2 1 15.7 2018-01-18 3 3 2 14.9 2018-02-
id id_customer id_service amount date
1 1 1 50.0 2018-01-10
2 2 1 15.7 2018-01-18
3 3 2 14.9 2018-02-07
4 1 3 700.0 2018-02-28
5 2 1 250.0 2018-03-19
6 3 2 315.7 2018-03-08
7 1 1 100.0 2018-04-28
8 2 2 132.0 2018-04-26
我想按2018年的月份进行汇总,并得出如下结果:
amount month
65.7 1
714.9 2
565.7 3
232.0 4
这是我的选择,我需要帮助
select sum(amount),extract(month from date) from evidence where extract(year from date)=2018 and amount>0 group by date;
像这样
SELECT SUM(amount) AS amount , date_trunc('month', date) as month
FROM evidence
WHERE extract(year from date)=2018
GROUP BY month
按摘录分组(从日期算起的月份)
否则,您将按实际日期分组,这将为每个源记录提供一个组。您希望按每月分组,而不是按日期分组。