Question

I know the title isn't so describing but it's really hard to find something generic to describe my situation. If someone wants to edit, feel free...

So, I have a postgres database, with a users table. I would like to store the users followed by one user, and I really don't see how I could do this. I would like to do like SELECT followed_users FROM users WHERE username='username' and this would return me every usernames, or id, or whatever of each followed users. But I don't see any clean way to do this.

Maybe an example would be more describing: user1 is following user2 and user3.
How to store who user1 is following?

EDIT: I don't know how many users the user will follow.

Thank you for your help.

Answer 1

扩展我上面的评论，因为它变得罗嗦了：

使用

等列创建一个名为user_follows的新表

user_id1 | user_id2

或

follower_id | follows_id

然后你可以查询：

SELECT t1.username as follower_username, t3.username as following_usernae
FROM users t1
    INNER JOIN user_follows t2 ON t1.user_id = t2.follower_id
    INNER JOIN users t3 ON t2.following_id = t3.user_id
WHERE t1.user_id = <your user>

最后，将您的表视为＆＃34; Objects＆＃34;。然后，当您遇到类似＆＃34的问题时;如何添加跟随其他用户的用户＆＃34;您可以确定此关系是新对象还是现有对象的属性。由于用户可能跟随多个其他用户而不是关系不是＆＃34;用户＆＃34;的良好属性，因此它获得自己的表user_follows。

由于user_follows只是两个用户可能彼此之间的一种关系，因此将该对象的范围增加到relationships并将关系类型存储为属性是有意义的。表：

user_id1 | user_id2 | relationship_type

其中relationships.relationship_type可能包含follows, student of, sister等值...

所以新查询会是这样的：

SELECT t1.username as follower_username, t3.username as following_username
FROM users t1
    INNER JOIN relationships t2 ON t1.user_id = t2.user_id1
    INNER JOIN users t3 ON t2.user_id2 = t3.user_id
WHERE t1.user_id = <your user> AND t2.relationship_type = 'Follows';

Answer 2

我要添加另一个表，让我们将其称为following以便参数，这样可以保存他们所关注的用户和用户对：

CREATE TABLE following (
    user_id INT NOT NULL REFERENCES users(id), 
    following_id INT NOT NULL REFERENCES users(id),
    PRIMARY KEY (user_id, following_id)
)

然后，您可以通过加入users表（两次）来查询特定用户所关注的所有用户。例如，获取我（用户名“mureinik”）所关注的所有用户的姓名：

SELECT fu.username
FROM   following f
JOIN   users u ON f.user_id = u.id
JOIN   users fu ON f.user_id = fu.id
WHERE  u.username = 'mureinik'

Best way to store followed users

2 个答案: