php - How to retrieve a chat msg with sender and receiver username in mysql -

chat table ------------------------------------------------------- msg_id  msg(description of msg)   sender(id)   receiver(id) ------------------------------------------------------- 1       hello                      2             1 1       how                1             2 ----------------------------------------------------------  user table ----------------------- u_id   username ----------------------- 1       usman 2       ali --------------------- 

here see 2 tables 1 chat , 1 table user make relationship between these 2 table feel difficulty how extract data these table.

what want..

i want extract each sender msg username , each reciver name username facebook chat make query

i put query in database

select u.user_name username,msg.msg user u,messages msg  (msg.sender or msg.receiver)=(select u_id user u_id= 1 )     , msg.sender=1 order msg.msg_id desc 

but query repeat sender message receive name , receiver msg sender name

i want show sender , reciver msg show separably name tell me method how fix it.

what have never work. or comparison return boolean true/false value, compare against value of u_id. , since u_id query hardcoded return 1, you're doing where true/false = 1.

you need join user table twice (once receiver, once sender):

select sender.user_name, receiver.user_name, msg.msg msg left join user sender on msg.sender_id = sender.u_id left join user receiver on msg.receiver_id = receiver.u_id order msg.msg_id