Useful Codes in magento

Redirection in Magento Controllers.

Mage::app()->getResponse()->setRedirect(Mage::getUrl('customer/account/login')); 

How to run an custom query in magento?

$sql = "SELECT * FROM your_table"; 

$getData = Mage::getSingleton('core/resource') ->getConnection('core_read')->fetchAll($sql); 

foreach($getData as $row) { 

    echo $row['name'] . "\n"; 

} 

// fetch write database connection that is used in Mage_Core module 

$write = Mage::getSingleton('core/resource')->getConnection('core_write'); 

// now $write is an instance of Zend_Db_Adapter_Abstract 

$write->query("insert into yourtablename values ('val1','val2')");

//or you can do it like this 

$write = Mage::getSingleton('core/resource')->getConnection('core_write'); 

$sql  = "insert into yourtablename values (?, ?)"; 

$write->query($sql, array('val1','val2'));

Get Customer Data

$customerData = Mage::helper('customer')->getCustomer()->getData());