mysql查询检查用户是否投票

Question

在这种情况下我有

帖子表：

id 
title
description

post_votes table：

id
post_id
user_id

评论表：

id
post_id
user_id
content

用户表：

id
username

我查询了我的索引页面（已登录的用户）

select 
`posts`.`id`, 
`posts`.`title`, 
`posts`.`description`,  
COUNT(distinct post_votes.id) AS votes, 
COUNT(distinct comments.id) AS comments 
from `posts` 
left join `post_votes` on `post_votes`.`post_id` = `posts`.`id` 
left join `comments` on `comments`.`post_id` = `posts`.`id` 
group by `posts`.`id`

这显示所有帖子（事件）。每一个都显示总票数和评论数量。另外，在索引页面上显示每个帖子的投票按钮。

用户可以对文章进行投票，我希望能够检查用户是否已经对每个帖子进行了投票，并且在这种情况下显示已禁用此帖子的投票按钮。

我有用户ID。

我该怎么办？

Answer 1

不确定mysql格式，但这样的事情应该有效：

select 
CASE WHEN userVote.post_id IS NULL THEN 'No user vote' ELSE 'User has voted' END AS 'VoteStatus'
`posts`.`id`, 
`posts`.`title`, 
`posts`.`description`,  
COUNT(distinct post_votes.id) AS votes, 
COUNT(distinct comments.id) AS comments 
from `posts` 
left join `post_votes` on `post_votes`.`post_id` = `posts`.`id`
left join `post_votes` AS userVote on `post_votes`.`post_id` = `posts`.`id` AND `post_votes`.`user_id` = @myUserID
left join `comments` on `comments`.`post_id` = `posts`.`id` 
group by `posts`.`id`