Doctrine\DBAL\Platforms\OraclePlatform::getForeignKeyReferentialActionSQL PHP Метод

    public function getForeignKeyReferentialActionSQL($action)
    {
        $action = strtoupper($action);
        switch ($action) {
            case 'RESTRICT':
                // RESTRICT is not supported, therefore falling back to NO ACTION.
            // RESTRICT is not supported, therefore falling back to NO ACTION.
            case 'NO ACTION':
                // NO ACTION cannot be declared explicitly,
                // therefore returning empty string to indicate to OMIT the referential clause.
                return '';
            case 'CASCADE':
            case 'SET NULL':
                return $action;
            default:
                // SET DEFAULT is not supported, throw exception instead.
                throw new \InvalidArgumentException('Invalid foreign key action: ' . $action);
        }
    }