sql：根据 group by 查找到最大创建日期小于某时间

根据 group by 查找最大创建日期小于某时间的：

select company_id from market_prices  group by company_id having max(created_at) < '2020-02-02 23:59:59'

根据 group by 查找最大创建日期小于某时间的且符合一定条件的公司数量：

select count(*) from (select distinct company_id from market_prices  group by company_id having max(created_at) < '2020-02-02 23:59:59') temp inner join companies on companies.id = temp.company_id where companies.is_hidden = false