Question

I have these information :
Table “Users” =>

 **Id**     **Name** 
   1           a
   2           b
   3           c
   4           d
   5           e

Table “Friends” =>

**SenderId**  **ReceiverId**    **State**
     1              2              x 
     2              3              ok 
     3              1              ok
     3              4              ok
     5              3              ok 
     5              4              ok

Table “Events” =>

     **SenderId**    **receiverId**     **text**
 1        1                3              ssss
 2        3                1             dsadsa
 3        2                3             safsdf
 4        3                5              fgfdgfd
 5        4                3             fgfhgfh
 6        5                4              sad sad

My question is that how could I get the events of user’s friends in one sql statement using JOINS only .

for example :=>

• userId : 1
• his friends : 3 (state = ok)
• friends events : 1, 2, 3, 4, 5 (events from 1 to 5 have the userId 3 which considered as a friend to user 1 )

ANY HELP .. THANKS 😉 !!

Answer 1

You didn’t specify a name for the first column in your Events table so I’ve called it row_ID:

SELECT U1.ID AS user_ID, U1.Name AS user_name, 
       U2.ID AS friend_user_ID, U2.Name AS friend_user_name, 
       E1.row_ID, E1.text AS event_text
  FROM Users AS U1
       INNER JOIN Friends AS F1
          ON (
              U1.ID = F1.ReceiverId
              OR U1.ID = F1.SenderId
             )
             AND F1.State = 'ok'
       INNER JOIN Users AS U2
          ON U2.ID = F1.SenderId
       INNER JOIN Events AS E1
          ON (
              U2.ID = E1.ReceiverId
              OR U2.ID = E1.senderId
             )
 WHERE U1.ID = 1;