gistfile1.php

<?php

/*  desc artists_similar;
+-------------------+------------------+------+-----+---------+----------------+
| Field             | Type             | Null | Key | Default | Extra          |
+-------------------+------------------+------+-----+---------+----------------+
| id                | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| artists_id        | int(10) unsigned | NO   | MUL | NULL    |                |
| similar_artist_id | int(10) unsigned | NO   |     | NULL    |                |
+-------------------+------------------+------+-----+---------+----------------+
*/

class ArtistsSimilar extends Phalcon\Mvc\Model {
  public function initialize(){
    $this->belongsTo('artists_id', 'Artists', 'id', array(
      'alias' => 'artist'
    ));
    $this->belongsTo('similar_artist_id', 'Artists', 'id', array(
      'alias' => 'similarArtist'
    ));
  }
}

/* Using getters */
$artist = ArtistsSimilar::findFirst()->getArtist();
$similarArtist = ArtistsSimilar::findFirst()->getSimilarArtist();

/* PHQL */
$phql = "SELECT * FROM ArtistsSimilar JOIN Artists WHERE id = 100";
$em->executeQuery($phql);