今天在分析Magento源代码的时候,在文件app/code/core/Mage/Catalog/Model/Resource/Eav/Mysql4/Config.php 中追踪到下面的函数 getAttributesUsedInListing()
/**
* Retrieve Product Attributes Used in Catalog Product listing
*
* @return array
*/
public function getAttributesUsedInListing() {
$select = $this->_getReadAdapter()->select()
->from(array(’main_table’ => $this->getTable(’eav/attribute’)))
->join(
array(’additional_table’ => $this->getTable(’catalog/eav_attribute’)),
‘main_table.attribute_id = additional_table.attribute_id’,
array()
)
->joinLeft(
array(’al’ => $this->getTable(’eav/attribute_label’)),
‘al.attribute_id = main_table.attribute_id AND al.store_id = ‘ . (int) $this->getStoreId(),
array(’store_label’ => new Zend_Db_Expr(’IFNULL(al.value, main_table.frontend_label)’))
)
->where(’main_table.entity_type_id=?’, $this->getEntityTypeId())
->where(’additional_table.used_in_product_listing=?’, 1);
– $sql = $select->assemble();
– echo $sql;
return $this->_getReadAdapter()->fetchAll($select);
}
Magento 操作数据库是在 Zend DB(Zend Framework)的基础上简单的做了下封装了。Zend DB 有自己的一套规则,来组合生成最终的SQL查询语句,可以看到上面的代码中有 from() join() ...