How to join two columns to the same table [duplicate]

Answer 1

You need to join twice to the table with the user data - once for each user involved:

select uf.username from_username, ut.username to_username, message
from messages m
join aspnet_Users uf on uf.id = userfrom
join aspnet_Users ut on ut.id = userto

This sql will work in both databases you have tagged the question with (or any other).

Answer 2

Just join with the user table twice.

SELECT
  t2.name AS userFrom,
  t3.name AS userTo,
  t1.Message
FROM messages t1
LEFT JOIN aspnet_Users t2 ON t1.UserFrom = t2.UserId
LEFT JOIN aspnet_Users t3 ON t1.UserTo = t3.UserId

Answer 3

You need to join aspnet_Users table twice with different alias names:

SELECT U1.Username as UserFrom,U2.Username as UserTo, M.Message
FROM Messages M JOIN
     aspnet_Users U1 ON U1.UserId=M.UserFrom JOIN
     aspnet_Users U2 ON U2.UserId=M.UserTo

Explanation:

Here aspnet_Users table it joined twice with different alias names U1,U2. And each username is fetched from the respective table.