Question

I have two table:

Users                          Mail
-------                        ------
ID | Username                  ID | UserID | SenderID   | Something
---------------                ---------------------------------------------------
1  | A                         1  |  2     |  1         | Becoming Mad with SQL
2  | B                         2  |  3     |  4         | Mee too

I am trying this:

SELECT *
 a.userid, a.senderid, a.something,
 b.username
FROM
 mail a
 LEFT JOIN users b on b.id=a.senderid
WHERE
 a.id='1'

Output is/similar:

a.Userid | a.senderid | a.something | b.username
--------------------------------------------------
2      | 1            | becoming..  | A

My Expected output is like this (username B and A in one row):

Userid | senderid | something | username | Username of UserID
---------------------------------------------------------------
2      | 1        | becoming..| A        | B

How can i get UserID and its Username in the same query? Because i already have left join users b on b.id=a.senderid

Answer 1

SELECT  a.userid, 
        a.senderid, 
        a.something,
        b.username, 
        c.username
FROM    mail a
        LEFT JOIN users b ON b.id = a.senderid
        JOIN      users c ON c.id = a.UserID
WHERE   a.id='1'