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gogogo1203
V2EX  ›  MySQL

请教 psql 多个表 Join+ count 的问题

  •  
  •   gogogo1203 · 98 天前 · 730 次点击
    这是一个创建于 98 天前的主题,其中的信息可能已经有所发展或是发生改变。
    我 google 了快 1 个小时了,实在找不出答案。 谢谢了。

    SELECT t.*,
    tt.tag_name,
    CASE WHEN COUNT(c.tutorial_id) > 0 THEN TRUE ELSE FALSE END AS collected,
    CASE WHEN COUNT(l.tutorial_id) > 0 THEN TRUE ELSE FALSE END AS liked,
    COUNT(lc.tutorial_id) as likecount
    FROM
    tutorials t
    LEFT JOIN
    collections c ON t.tutorial_id = c.tutorial_id AND c.user_id = 'ec02a580-f9cd-4941-94c4-13a0c86246e3'
    LEFT JOIN
    likes l ON t.tutorial_id = l.tutorial_id AND l.user_id = 'ec02a580-f9cd-4941-94c4-13a0c86246e3'
    LEFT JOIN
    likes lc ON t.tutorial_id = lc.tutorial_id
    LEFT JOIN
    tutorials_tags tt on t.tutorial_id = tt.tutorial_id
    WHERE
    t.tutorial_id = '78e76b5b-9699-47a4-9c41-2c2f1cfb4059'
    GROUP BY 1


    ERROR: column "tt.tag_name" must appear in the GROUP BY clause or be used in an aggregate function

    query 从表 like 里数这个 tutorial_id 有多少 like 和用户是否喜欢, 从 collections 查用户是否已经收藏, 从 tag 里查 tag_name. 我卡在 tag_name 不能 group by.
    麻烦了!
    3 条回复    2022-05-18 23:29:09 +08:00
    lichao
        1
    lichao  
       97 天前
    GROUP BY 1 ?? 你这么写,用意是什么?
    gogogo1203
        2
    gogogo1203  
    OP
       97 天前
    @lichao 不然怎么用 count? 这里的 by 1 或者 by t.tutorial_id 都是一样的。你是有更好的方法?
    gogogo1203
        3
    gogogo1203  
    OP
       91 天前
    找到解决方案了.
    const q = `
    SELECT
    a.*, u.image
    FROM (
    SELECT
    t.tutorial_id, t.username, t.version, t.date_created, t.date_updated, t.tag_name, t.slug, t.title,t.description, t.content, t.published, t.deleted, t.date_deleted,
    CASE WHEN COUNT(c.tutorial_id) > 0 THEN TRUE ELSE FALSE END AS collected,
    CASE WHEN COUNT(l.tutorial_id) > 0 THEN TRUE ELSE FALSE END AS liked,
    c.user_id,
    COUNT(l.tutorial_id) as likecount
    FROM
    collections c
    JOIN
    tutorials t ON t.tutorial_id = c.tutorial_id
    LEFT JOIN
    likes l on c.tutorial_id = l.tutorial_id AND l.user_id = c.user_id
    LEFT JOIN
    likes lc ON c.tutorial_id = lc.tutorial_id
    WHERE
    c.user_id = :user_id
    GROUP BY c.user_id, t.tutorial_id
    ) a
    JOIN
    users u USING(user_id)
    WHERE
    a.user_id = :user_id
    AND
    a.deleted = FALSE
    `
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