Question

I have three database tables: users, user_profiles and friends:

users

• id
• username
• password

user_profiles

• id
• user_id
• full_name

friends

• id
• usera_id
• userb_id

What would be a query which finds the friends list of any user and also joins the table users and user_profiles to get the profile and user information of that friend?

Answer 1

Use:

SELECT f.username,
       up.*
  FROM USERS f
  JOIN USER_PROFILES up ON up.user_id = f.id
  JOIN FRIENDS fr ON fr.userb_id = f.id
  JOIN USERS u ON u.id = fr.usera_id
 WHERE u.username = ?

…assuming userb_id is the friend id.