Question

SELECT帖子，其最后3条评论和所有评论的数量我的代码：

SELECT p.*, u.id, u.username username, u.usersurname usersurname, u.usermainphoto userphoto, GROUP_CONCAT(c.text SEPARATOR 'a!k@h#md%o^v&') commenttext,GROUP_CONCAT(c.likes SEPARATOR '-') commentlikes,GROUP_CONCAT(c.dislikes SEPARATOR '-') commentdislikes, GROUP_CONCAT(c.commentdate) commentdate, GROUP_CONCAT(u2.username) commentauthorname, GROUP_CONCAT(c.anonim) commentanonym, GROUP_CONCAT(c.id) commentid, GROUP_CONCAT(u2.id) commentauthorid, GROUP_CONCAT(u2.usersurname) commentauthorsurname, GROUP_CONCAT(u2.usermainphoto) commentauthorphoto, GROUP_CONCAT(c.commentphotoid) commentphotoid
FROM posts p
LEFT JOIN comments c ON c.post = p.postid AND c.commentdel=0
LEFT JOIN users u ON u.id = p.postauthorid
LEFT JOIN users u2 ON u2.id = c.author
WHERE p.postwallid = :id AND p.postdel=0
GROUP BY postid
ORDER BY postid DESC

它给了我所有评论，但我只需要3

Answer 1

您需要一个时间戳或计数器来确定哪些评论是您想要的三个。在下面的尖括号之间添加该列名。

SELECT p.*, u.id, u.username username, u.usersurname usersurname, u.usermainphoto userphoto, GROUP_CONCAT(c.text SEPARATOR 'a!k@h#md%o^v&') commenttext,GROUP_CONCAT(c.likes SEPARATOR '-') commentlikes,GROUP_CONCAT(c.dislikes SEPARATOR '-') commentdislikes, GROUP_CONCAT(c.commentdate) commentdate, GROUP_CONCAT(u2.username) commentauthorname, GROUP_CONCAT(c.anonim) commentanonym, GROUP_CONCAT(c.id) commentid, GROUP_CONCAT(u2.id) commentauthorid, GROUP_CONCAT(u2.usersurname) commentauthorsurname, GROUP_CONCAT(u2.usermainphoto) commentauthorphoto, GROUP_CONCAT(c.commentphotoid) commentphotoid
FROM posts p
LEFT JOIN comments c ON c.post = p.postid AND c.commentdel = 0
LEFT JOIN users u ON u.id = p.postauthorid
LEFT JOIN users u2 ON u2.id = c.author
WHERE p.postwallid = :id AND p.postdel = 0
    and (
        select count(*) from comments as c2
        where c2.postid = p.postid and c2.commentdel = 0
        and c2.<timestamp> <= c.timestamp
    ) < 3
GROUP BY postid
ORDER BY postid DESC

编辑：我没有添加所有评论的计数。我认为您可以在选择列表中轻松添加另一个子查询，但我知道MySQL人员不太喜欢子查询。

(
select count(*) from comments as c2
where c2.postid = c.postid and c2.commentdel = 0
) as comment_count

Answer 2

我将SELECT count（postid）添加为all_comments，最后是LIMIT 0,3

SELECT count(postid) as all_comments, p.*, u.id, u.username username, u.usersurname usersurname, u.usermainphoto userphoto, GROUP_CONCAT(c.text SEPARATOR 'a!k@h#md%o^v&') commenttext,GROUP_CONCAT(c.likes SEPARATOR '-') commentlikes,GROUP_CONCAT(c.dislikes SEPARATOR '-') commentdislikes, GROUP_CONCAT(c.commentdate) commentdate, GROUP_CONCAT(u2.username) commentauthorname, GROUP_CONCAT(c.anonim) commentanonym, GROUP_CONCAT(c.id) commentid, GROUP_CONCAT(u2.id) commentauthorid, GROUP_CONCAT(u2.usersurname) commentauthorsurname, GROUP_CONCAT(u2.usermainphoto) commentauthorphoto, GROUP_CONCAT(c.commentphotoid) commentphotoid
FROM posts p
LEFT JOIN comments c ON c.post = p.postid AND c.commentdel=0
LEFT JOIN users u ON u.id = p.postauthorid
LEFT JOIN users u2 ON u2.id = c.author
WHERE p.postwallid = :id AND p.postdel=0
GROUP BY postid
ORDER BY postid DESC
LIMIT 0, 3

SELECT帖子，其最后3条评论和所有评论的计数

2 个答案: