magento sql 用法

		$resource = Mage::getSingleton('core/resource');
		$tableName_votes = $resource->getTableName('jselfless/votes');
		$tableName_image = $resource->getTableName('jselfless/image');
		$collection = Mage::getModel('jselfless/woman')->getCollection();
		$collection->getSelect()->reset(Zend_Db_Select::COLUMNS);
		$collection->getSelect()->columns(array('items_count'=>'count(main_table.id)'));  
		$collection->addFieldToFilter('main_table.year',date('Y'));
		$collection->addFieldToFilter('image.type','main');
		$collection->addFieldToFilter('award',array('eq'=>''));
		$collection->getSelect()->join(array('votes' => $tableName_votes), 'main_table.id = votes.selfless_woman_id', '');
		$collection->getSelect()->join(array('image' => $tableName_image), 'main_table.id = image.selfless_woman_id', array('image.*'));
		$collection->getSelect()->group('main_table.id');
		$collection->getSelect()->Order('items_count  desc');
		$collection->getSelect()->Order('votes.created_at  desc');  
		$collection->getSelect()->Order('main_table.updated_at  desc'); 
		$collection->getSelect()->limit(10,$postData['offset']);

一些常用的用法，记录一下；