/** * @return string */ private function keys() { if (count($this->_primary_keys) > 0) { $lead = ' PRIMARY KEY ('; $quoted = array(); foreach ($this->_primary_keys as $key) { $quoted[] = sprintf("%s", $this->_adapter->identifier($key)); } $primary_key_sql = ",\n" . $lead . implode(",", $quoted) . ")"; return $primary_key_sql; } else { return ''; } }