需要找到一个查询以在MySQL中返回某些结果

Question

I have two tables, User and relationshp. I need to find all the users who have sent the logged in user a friend request.

User Table                        relationship Table
------------         ----------------------------------------------
id | username         user_one_id | user_two_id | status | action_user_id

Those are my two tables. user_one_id is the user who sent the request, while user_two_id is the recipient.

I need to find a query that will return all friend request received by the logged in user.

If tried the following, but it only returned only the name of the user logged in and the id of the users who sent them the request. Did not return the names of the sender.

 var loggedInUser = req.user[0];
 connection.query("
 SELECT User.id, User.username, relationship.user_one_id, 
 relationship.status 
 FROM User INNER JOIN relationship ON User.id=relationship.user_one_id 
 WHERE User.id = ?",
 [loggedInUser], function(err, results, fields) {}

Any help would be greatly appreciated.

Answer 1

You would need to use two INNER JOIN statements in your query, one for user_one_id and another for user_two_id :

SELECT userA.id, userA.username, userB.id, userB.username, status, action_user_id
FROM relationship
INNER JOIN User AS userA ON userA.id = relationship.user_one_id
INNER JOIN User AS userB ON userB.id = relationship.user_two_id
WHERE userA.id = ?

UPDATED ANSWER:

See link here for more details: http://sqlfiddle.com/#!9/af7ce/5

SELECT userA.id AS userA_id, userA.username AS userA_username, userB.id AS userB_id, userB.username AS userB_username, status, action_user_id, userC.username AS action_user_username
FROM relationship
INNER JOIN User AS userA ON userA.id = relationship.user_one_id
INNER JOIN User AS userB ON userB.id = relationship.user_two_id
INNER JOIN User AS userC ON userC.id = relationship.action_user_id
WHERE (userA.id = 1 OR userB.id = 1) AND userC.id != 1