ios - 数据库逻辑问题

Answer 1

大概思路

 select (close-open) as useTime from (select case when openTime<3600*i then 3600*i else openTime end as open,case when closeTime >3600*i+3600 then 3600*i+3600 else closeTime end as close from tabel where openTime <= 3600*I and closeTime>=3600*i )

好久没写sql了，语句不知道会不会有问题