Two Foreign Keys Refer same column of another table?

Question

I have two relations like this, user(user_id, user_name) messages(sender,reciever,time,message) in here both sender and reciever refers user_id of the user table. I need to write a query to get sender's user_name recievers user_name , message.

Answer 1

You need to JOIN with the referring table twice like

select u1.user_name as Sender,
u2.user_name as Receiver,
m.message
from messages m
join user u1 on m.sender = u1.user_id
join user u2 on m.receiver = u2.user_id;