public function createPkCriteria($table,$pk,$condition='',$params=array(),$prefix=null)
	{
		$this->ensureTable($table);
		$criteria=$this->createCriteria($condition,$params);
		if($criteria->alias!='')
			$prefix=$this->_schema->quoteTableName($criteria->alias).'.';
		if(!is_array($pk)) // single key
			$pk=array($pk);
		if(is_array($table->primaryKey) && !isset($pk[0]) && $pk!==array()) // single composite key
			$pk=array($pk);
		$condition=$this->createInCondition($table,$table->primaryKey,$pk,$prefix);
		if($criteria->condition!='')
			$criteria->condition=$condition.' AND ('.$criteria->condition.')';
		else
			$criteria->condition=$condition;

		return $criteria;
	}