基于移动日期窗口的条件求和的SQL查询。

I'm trying to figure out some sliding window stats on my users. I have a table with a user, and columns such as created_at and verified_at. For each month, I'd like to find out how many users registered (a simple group by date_trunc of the created_at), and then of those people, how many verified within my sliding window (call it 60 days).I'm trying to figure out some sliding window st