public function addPrimaryKey($name,$table,$columns)
	{
		echo "    > alter table $table add constraint $name primary key (".(is_array($columns) ? implode(',', $columns) : $columns).") ...";
		$time=microtime(true);
		$this->getDbConnection()->createCommand()->addPrimaryKey($name,$table,$columns);
		echo " done (time: ".sprintf('%.3f', microtime(true)-$time)."s)\n";
	}