A dropdown list can be used to select a value, based on which we can filter the data to be displayed. For example, the extension page has a dropdown list to filter the displayed extensions according to the selected category.
A simple and effective way to keep track what your users are doing within your application is to log their activities related to database modifications. You can log whenever a record was inserted, changed or deleted, and also when and by which user this was done. For a CActiveRecord Model you could use a behavior for this purpose. This way you will be able to add log functionality to ActiveRecords very easily.
Some PHP installations may use a different php.ini file for CLI PHP (command line PHP parser). As a result, when running the model or crud command in yiic shell, you may encounter errors like "YiiBase::include(PDO.php): failed to open stream..." or "...could not find driver", even though the requirement checker confirms you have PDO and the corresponding database driver.
By default, the expression Yii::app()->user returns a CWebUser application component which represents the information that are closely related with the current user. Some information can be persistent throughout the current user session. For example, CWebUser already comes with a name property that stores the username of the current user.