SQL查询根据移动日期窗口有条件地求和

我试图找出我的用户的滑动窗口统计信息.我有一个用户的表和列,如created_at和verified_at.每个月,我想知道有多少用户注册(一个简单的group by date_trunc的created_at),然后是那些人,在我的滑动窗口内验证了多少(称为60天).

我想做一个SQL查询,给我一些像：

Month    | Registered | Verified in 60 days
Jan 2009 | 1543       | 107
Feb 2009 | 2000       | 250

我正在使用postgresql.我开始查看sum(case …),但是我不知道我是否可以让我的case被依赖于date_trunc.

这当然不行,但这里的想法是：

SELECT DATE_Trunc('month',created_at) as month,COUNT(*) as registered,SUM(CASE WHEN verified_at < month+60 THEN 1 ELSE 0 END) as verified
FROM users
GROUP BY DATE_Trunc('month',created_at)

解决方法

SELECT  COUNT(created_at) AS registered,SUM(CASE WHEN verified_at <= created_at + '60 day'::INTERVAL THEN 1 ELSE 0 END) AS verified
FROM    generate_series(1,20) s
LEFT JOIN
        users
ON      created_at >= '2009-01-01'::datetime + (s || ' month')::interval
        AND created_at < '2009-01-01'::datetime + (s + 1 || ' month')::interval
GROUP BY
        s