从两个以上的表中选择使用连接选择重复项

Question

我在我的mysql数据库（用户，关注者，发布）上有3个表，我写了一个sql，获取用户所关注人员的所有帖子。

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 

FOL下表

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

交表

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 

所以现在我想选择的人的用户在下面的帖子和用户的

我想这SQL的帖子

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 

请就是想实现与SQL可能， 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; 

Answer 2

试试这个：

SELECT Distinct post.* FROM post JOIN 
    follower ON post.owner_user_id = follower.user_id JOIN 
    user ON follower.user_id = user.id WHERE user.id = 3 

您shuldn​​'t使用条件JOIN语句，使用WHERE代替。