Get field data without load node

field.php

  $field_name = 'field_banner_media';
  $field_info = field_info_field($field_name);
  $field_id   = $field_info['id'];

  $nids  = array($banner_top);
  $sql   = 'SELECT * FROM {node} WHERE nid IN (:nids)';
  $nodes = db_query($sql, array(':nids' => $nids))->fetchAllAssoc('nid');
  field_attach_load('node', $nodes, FIELD_LOAD_CURRENT, array('field_id' => $field_id));

  $field_banner     = field_get_items('node', reset($nodes), $field_name);
  $field_banner_url = isset($field_banner[0]['uri'])? file_create_url($field_banner[0]['uri']): NULL;