Table structure for PHP friendship systems

Question

I am developing a system of friendships in my system and would like to know the best way to organize the table that will take care of such records amigos:

I’ve thought of something:

Tabela "amigos" (apenas 3 colunas)
-----------------------------------
   id | usuario | usuarioamigo

However I do not know if it is the best way to do and much less how could do the query relationship to know if a user is a friend of another user.

What’s the best way to do it and how to do it?

Answer 1

This is the simplest way having user and friend. In the query you check whether User ID matches the ID of friend and vice versa, in usuario or in usuarioamigo

select * from amigos
where ( usuario = $IDUser or usuarioamigo = $IDUser )
  and ( usuario = $amigo  or usuarioamigo = $amigo  )

_{reference 1 , reference 2}