SQL查询从表中获取多次信息

Question

This is very easy for experimented Sql users i guess:

given the following tables:

Table users

   id  Name
   1 | Stephan
   2 | Marion
   3 | Jonathan
   4 | Morgan

Table messages

  id| sender | reveiver | message
   1|    2   |     4    | "hello world!"

How would you do your request to get the following(in only one sql request) :

 id| sender | reveiver | message        | sender.username | receiver.username
  1|    2   |     4    | "hello world!" |       Marion    |        Morgan

Thanks a lot!

Answer 1

select m.id, sender, reveiver, message,
  sender.Name as sender_username, receiver.Name as receiver_username
from messages m
inner join users sender on sender.id = m.sender
inner join users receiver on receiver.id = m.reveiver