mysql - 如何一起选择帖子和共享帖子？

Question

我有一个系统，用户可以发帖和分享其他 friend 的帖子，比如在 Facebook 上。

问题是我想同时从帖子和共享帖子中获取数据，我的意思是，按照顺序，但是帖子在表帖子上，共享帖子在表共享上:

CREATE TABLE IF NOT EXISTS `posts` (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `user` int(11) UNSIGNED NOT NULL,
  `titulo` text,
  `data` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 AUTO_INCREMENT=1 ;

CREATE TABLE IF NOT EXISTS `share` (
  `id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
  `user` int(11) UNSIGNED NOT NULL,
  `share_post_id` int(11) UNSIGNED NOT NULL,
  `data` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 AUTO_INCREMENT=1 ;

我有这个选择来获取帖子:

select c.nome, c.user, p.user, p.id, p.data, p.titulo, pp.foto, count(DISTINCT likes.user) as likes_count, count(distinct comentarios.id) as comentarios_count, count(DISTINCT l2.user) as count2 from posts p 
join cadastro c on p.user=c.id 
left join profile_picture pp on p.user = pp.user
left join likes on likes.post = p.id
left join comentarios on comentarios.foto = p.id and comentarios.delete = 0  
left join likes l2 on l2.post = p.id and l2.user = ?
group by p.id
order by p.id desc limit 20

如何将共享帖子与此选择中的帖子一起获取？有什么想法吗？

Answer 1

您可以通过简单地执行 union all 并将缺少的列添加为 NULL 来做到这一点!

     SELECT id,`user`,`data`,`titulo`,NULL as `share_post_id` from posts 
     union all 
     SELECT  id,`user`,`data`,NULL as `titulo`,`share_post_id` from `share`     order by id