php - 使用连接从两个以上的表中选择重复项

Question

我的 mysql 数据库上有 3 个表(用户、关注者、帖子)，我写了一个 sql，它从用户关注的人那里获取所有帖子。

sql

SELECT post.* FROM post JOIN
       follower ON post.owner_user_id = follower.user_id AND
       follower.follower_id = "3"

结果

id | owner_user_id | content
2  | 1             | why are all my senior developers jerks?
3  | 1             | PHP7 in your face node.js

用户表

id | username | password
 1 | user1    | 12345678
 2 | user2    | 12345678
 3 | user3    | 12345678

跟随表

user_id | follower_id
3       | 1
3       | 2
1       | 3

张贴表格

id | owner_user_id | content
1  | 2             | reading a 1k+ page on mysql, do i need to?
2  | 1             | why are all my senior developers jerks?
3  | 1             | PHP7!, in your face node.js
3  | 3             | I posted

所以现在我正在尝试选择用户关注的人的帖子和用户的帖子

我试过这个sql

sql

SELECT post.* FROM post JOIN
       follower ON post.owner_user_id = follower.user_id AND
       follower.follower_id = "3" JOIN
       user ON post.owner_user_id = user.id= "3"

结果

null

请问我试图用 sql 实现什么，如果(可能){“what_am_i_doing_wrong”}()；

编辑

user_id 3 has a post, still running the above sql returns null, was hoping if the user had no post, only post of the people the user is following is returned

Answer 1

select post.* from 
(select user_id from follower where follower_id = 3 union select 3) blah 
join post on blah.user_id = post.owner_user_id;