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Here in this post we will discuss how to work with database in Magento. As we know that Magento is enrich with MVC (Model – View – Controller). So we will basically starts with some main concepts of models, resource models, and collections.

Basic concepts of models, resource models, and collections

A “model” is used to store data, and perhaps performs some business logics against that data.

A “resource model” is used to interact with the database on behalf of the “model”. The “resource model” actually performs the CRUD operations.

A “collection model” holds from one to many “models” and knows how to tell the “resource model” to get rows in the basis of information it is given.

There’s a basic ActiveRecord-like/one-object-one-table Model, and there’s also an Entity Attribute Value (EAV) Model.

Configure a database connection

Create and register new entities

As we know that Zend_Db and its related classes provide a simple SQL database interface for Zend Framework. The Zend_Db_Adapter is the basic class you use to connect your PHP application to Mysql database.

Here we will use Zend_Db_Adapter_Pdo_Mysql classes to query the Database

Returns to the information of queries.

Zend_Db_Statement

Zend_Db_Table:

Each class interacts with one table in the database, and you need to declare the database table for which this class define.
Example:

With $table object, you can use some methods to operate with the database such as: insert, update, delete.

Zend_Db_Table_Row:

This will return the record object in the table

Zend_Db_Select:

Database collection in Magento

The collection in Magento usually extends from class Mage_Core_Model_Resource_ Collection_Abstract or Mage_Core_Model_Mysql4_ Collection_Abstract. The collection has some methods for you to filter, sort and specify the selected values:

• addFieldToFilter(,): used to filter data
• setOrder(): used to sort data
• getSelect(): returns the selected query (is instance object of class Varien_Db_Select) to this collections. And you are able to use it to add specific selected value.
• Database resource
  • abstract class Mage_Core_Model_Resource_Abstract
  • abstract class Mage_Core_Model_Mysql4_Abstract

The database model and the collection connect to database through database resource layer. The resource class extends from an abstract class:

In this class, you need to declare your database table and the id field of this table.

For example:

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1. public function _construct(){
2. $this->_init(‘affiliate/program’, ‘order_id’);
3. }

public function _construct(){<br /> $this->_init(‘affiliate/program’, ‘order_id’);<br /> }

We can also use and resolve existing table names without hard coding them

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1. $resource = Mage::getSingleton(‘core/resource’);
2. $eavAttributeTable = $resource->getTable(‘eav/attribute’);

$resource = Mage::getSingleton(‘core/resource’);<br /> $eavAttributeTable = $resource->getTable(‘eav/attribute’);<br />

“eav/attribute” here is your configuration for table eav_entity_attribute in your database.

Hope it will work for you!

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