Upgrade self customization is such customization in which if we upgrade Sugar version our customized part does not need any change or modification.
To overcome after up gradation problems we need to customize all our modules and other codes into custom folder.
If you directly have id use retrieve functionality. But if there any field value exist other than id use retrieve_by_string_fields function.
It takes an array as parameter and returns an object.
Example:
require_once(‘modules/Assets/Asset.php’);
$assetObj = new Asset();
$fieldArray = array(‘job_id’=>$_REQUEST['job_id']);
$asset = $assetObj->retrieve_by_string_fields($fieldArray);
Here array key ‘job_id’ is an existing field in asset table.