SQL Query INNER JOIN有三个表

Question

有这三个表：

1. 帖子
2. posts_replies
3. 喜欢

此查询返回我的帖子，他们的回复计数都很好。 SELECT posts.title，posts.num，posts.status，posts.category，posts.content，posts.member_num，COUNT（posts_replies.blyrb_num）AS count

FROM posts_replies
INNER JOIN posts ON ( posts_replies.blyrb_num = posts.num )
WHERE posts.status =1
AND posts.access = 'Public'
GROUP BY posts.num
ORDER BY count DESC
LIMIT 50 

记录此查询返回的是：47

这是一个有点更新的查询，我想在帖子上提取每个回复的喜欢计数。

SELECT posts.title, posts.num, posts.status, posts.category, posts.content, posts.member_num, 
COUNT( posts_replies.blyrb_num ) AS count,
COUNT( likes.comment_num  ) AS likes_count
FROM posts_replies
INNER JOIN posts ON ( posts_replies.blyrb_num = posts.num )
INNER JOIN likes ON ( likes.comment_num = posts_replies.num )
WHERE posts.status =1
AND posts.access = 'Public'
GROUP BY posts.num
ORDER BY count DESC
LIMIT 50 

此查询返回Likes Count，但不包括那些没有喜欢的记录。 所以此查询返回的记录是：40

我想包括每个回复的喜欢计数，即使它有0个喜欢。

任何帮助？

谢谢

Answer 1

使用LEFT JOIN代替INNER JOIN可能会对您有所帮助

SELECT posts.title, posts.num, posts.status, posts.category,
posts.content,posts.member_num, 
COUNT( posts_replies.blyrb_num ) AS count,
COUNT( likes.comment_num  ) AS likes_count
FROM posts_replies
INNER JOIN posts ON ( posts_replies.blyrb_num = posts.num )
LEFT JOIN likes ON ( likes.comment_num = posts_replies.num )
WHERE posts.status = 1
AND posts.access = 'Public'
GROUP BY posts.num
ORDER BY count DESC
LIMIT 50 

LEFT JOIN的想法是匹配行，即使在右侧没有匹配也是如此。 INNER JOIN仅在双方都有行时才有效。 ：）