private function changeColumns(): void
	{
		$change = [];
		foreach ($this->oldColumns as $name => $column) {
			if ($this->columnExists($name)) {
				$change[] = "[$name] $column";
			}
		}
		if (!empty($change)) {
			$this->connection->query("ALTER TABLE %table CHANGE " . implode(', CHANGE ', $change), $this->name);
		}
	}