问题描述
SELECT
ap.userid,ap.audioid,u.id
(
SELECT GROUP_CONCAT(t.tagname)
FROM entitytag et
LEFT JOIN tags t on t.tagid = et.tagid
WHERE et.audioid = ap.audioid
) tagname
FROM audioposts ap
LEFT JOIN users u ON u.id = ap.userid
但是现在我想添加另一个左联接,该联接计算一个称为“回复”的表中每个ap.audioid
的回复数。有人知道如何添加这个额外的左联接吗?
SELECT count('replyid') from replies WHERE opid = ?
但是如何将多余的左联接添加到第一个代码中,以便可以从每个audioid
的回复表中获取回复计数?
解决方法
没有左加入,但是阅读您的问题应该可以解决:
SELECT
ap.userid,ap.audioid,u.id,(
SELECT GROUP_CONCAT(t.tagname)
FROM entitytag et
LEFT JOIN tags t on t.tagid = et.tagid
WHERE et.audioid = ap.audioid
) tagname,(
select count('replyid') from replies WHERE opid = ap.audioid
) as count
FROM audioposts ap
LEFT JOIN users u ON u.id = ap.userid