复杂SQL查询……3个表，使用时间戳需要在过去24小时内最流行的

I have 3 tables with a column in each which relates to one ID per row. I am looking for an sql statement query which will check all 3 tables for any rows in the last 24 hours (86400 seconds) i have stored timestamps in each tables under column I have 3 tables with a column in each which rel