如何缩短这条sql语句？(3个子查询)
如何缩短这条sql语句？(3个子查询)
提问于 2020-05-06 09:03:45
我在缩短此查询sql /pdo时遇到问题。
我需要的是从特定用户的不同表中获取不同的值，例如：
User1
Number of posts:23
Number of Comments: 2745
Number of Likes: 654 (given to another posts)以下是查询：
SELECT
p.*,
(SELECT COUNT(*) FROM comments WHERE id_commenter = :id_session) AS no_comments,
(SELECT COUNT(*) FROM likes WHERE id_liker = :id_session) AS no_likes,
(SELECT COUNT(*) FROM posts WHERE id_poster = :id_session) AS no_topics
FROM
posts p
WHERE
p.id_poster = :id_session我试过这样的东西，但没有成功...
SELECT
COUNT(p.id_post) no_posts,
COUNT(c.id_comment) no_comments,
COUNT(l.id_like) no_likes,
FROM
users u
LEFT JOIN
comments c on c.id_user = u.id_user
LEFT JOIN
posts p on p.id_user = u.id_user
LEFT JOIN
likes l on l.id_user = p.id_user
WHERE
id_user = "1" 它没有按预期检索值，我如何缩短我的第一条SQL语句？我需要使用distinct吗？
回答 1
Stack Overflow用户
发布于 2020-05-06 09:05:37
我想你只是想：
SELECT (SELECT count(*) FROM comments WHERE id_commenter = :id_session) as no_comments,
(SELECT count(*) FROM likes WHERE id_liker = :id_session) as no_likes,
(SELECT count(*) FROM posts WHERE id_poster = :id_session ) as no_topics没有理由使用SELECT子句(除非您需要FROM dual或某些数据库需要的类似内容)。
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原文链接：
https://stackoverflow.com/questions/61625595
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