MySQL：连接的 24 小时间隔

Question

我有以下疑问：

select * from winners 
join profiles on winners.subscriber_id = profiles.subscriber_id 
join comments on comments.profile_id = profiles.vanity
join videos on winners.subscriber_id = videos.subscriber_id
join photos on winners.subscriber_id = photos.subscriber_id
where winners.round_id >= 4 AND winners.active = true 
AND (comments.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR) OR videos.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR) OR photos.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR)) AND comments.parent_id = 0;

此查询在 cron 作业上运行，该作业将提取每个获胜者过去 24 小时的最新信息，然后通过电子邮件向每个获胜者粉丝发送最新信息。

我遇到的问题是，如果在过去 24 小时内发生了对视频的评论，那么查询会拉回误报，那么它会拉回视频和评论。 是否有任何限制以获取过去 24 小时内发生的所有事情？

Answer 1

我会将 24 小时检查移至联接。这样我们只加入最近更新的项目。

select * from winners 
    join profiles on winners.subscriber_id = profiles.subscriber_id
    left join comments on (comments.profile_id = profiles.vanity AND comments.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR))
    left join videos on (winners.subscriber_id = videos.subscriber_id AND videos.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR))
    left join photos on (winners.subscriber_id = photos.subscriber_id AND photos.created_at > DATE_SUB( NOW(), INTERVAL 24 HOUR))
where winners.round_id >= 4 AND winners.active = true 
AND comments.parent_id = 0;