public function addForeignKey(string $name, $mapperClass, $onDelete = true, $onUpdate = false): Column
	{
		$table = $this->getTableData($mapperClass);

		$constrait = new Constrait($name, $this, $table, $onDelete, $onUpdate);

		$this->constraints[$constrait->name] = $constrait;
		return $constrait->column;
	}