对朋友表的待处理朋友请求查询并从其他表中获取数据-数据库问题

Pending friend request query for friends table and grabbing data from other tables(对朋友表的待处理朋友请求查询并从其他表中获取数据)

本文介绍了对朋友表的待处理朋友请求查询并从其他表中获取数据的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

要获得所选用户的待处理请求，我使用:

To get pending request for selected user I use:

SELECT f1.asker_user_id AS friend_id
FROM friends AS f1 
LEFT JOIN friends AS f2
    ON f1.asked_user_id = f2.asker_user_id
    AND f1.asker_user_id = f2.asked_user_id   
WHERE f1.status = 1 AND f2.status IS NULL
AND f1.asked_user_id = 2


http://www.sqlfiddle.com/#!2/0f7a0d5/65 正确返回用户 3.VALUES (3,2,1)
http://www.sqlfiddle.com/#!2/0f7a0d5/65 It correctly returns user 3. VALUES (3,2,1)
但我想获取有关此用户 3 的更多数据.
But I'd like to get more data about this user 3.

我需要 users 表中的 name_surname 和 avatar.并且该用户的所有 word_id 来自 connections 表，作为回报，该表将显示 words_en 中基于 words_en 的 wordcode>word_id.

I need name_surname and avatar from users table. And all word_ids of this user from connections table, which in return would show word from words_en based on word_id.

感谢分配！

附言我试过这个:

SELECT a.name_surname,GROUP_CONCAT(Distinct w.word Order by w.word asc) AS words
FROM (
  SELECT f1.asked_user_id AS friend_id,
       f1.created,
       u.name_surname,
       u.avatar
  FROM friends AS f1 
  LEFT JOIN friends AS f2 ON f1.asked_user_id = f2.asker_user_id
  INNER JOIN users AS u ON f1.asked_user_id = u.id
       AND f1.asker_user_id = f2.asked_user_id
  WHERE f1.status = 1 AND f2.status IS NULL
       AND f1.asker_user_id = 2
) a
LEFT JOIN connections c ON c.user_id = a.friend_id 
LEFT JOIN words_en w ON c.word_id = w.id
GROUP BY 1;

推荐答案

基于这个问题和你之前的问题，我想你可能正在寻找这样的东西:

Based on this question and your previous questions, i think you might be looking for something like this:

SELECT u.name_surname, 
       u.avatar,
       GROUP_CONCAT(DISTINCT w.word Order by w.word asc) AS words
FROM users u
INNER JOIN 
(
SELECT f1.asker_user_id AS friend_id
    FROM friends AS f1 
    LEFT JOIN friends AS f2
        ON f1.asked_user_id = f2.asker_user_id
        AND f1.asker_user_id = f2.asked_user_id   
    WHERE f1.status = 1 AND f2.status IS NULL
    AND f1.asked_user_id = 2
) a ON a.friend_id = u.id
LEFT JOIN connections c ON u.id = c.user_id
LEFT JOIN words_en w ON w.id = c.word_id
GROUP BY u.id;

sqlfiddle 演示

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