gistfile1.php

<?php

  /**
   * Get all users of a group who contributed.
   */
  function _events_resource_get_users_in_group($gid) {
    $query = db_select('og_membership', 'ogm');
    $query->join('node', 'n', "n.nid = ogm.etid AND ogm.entity_type = 'node'");
    $query->join('user', 'u', 'n.uid = u.uid');
    $query->fields('n', array('uid'))
      ->condition('n.status', 1)
      ->condition('u.status', 1);
  
    $result = $query->execute();
    return $result->fetchAll();
  }