Schema::createKeySql

protected Schema::createKeySql($fields)

protected function createKeySql($fields) {
  $return = array();
  foreach ($fields as $field) {
    if (is_array($field)) {
      $return[] = $field[0];
    }
    else {
      $return[] = $field;
    }
  }
  return implode(', ', $return);
}