The customary configuration of a Yii application includes just a single database section in the protected/config/main.php file, but it's easy to extend this to support more than one, tying each Model to one of the databases.
Occasionally one wishes to set systemwide parameters for an application, such as a contact address for email, an application name, or setting an option that guides major behavior. Yii provides for setting of static parameters in the configuration file, and this article talks about how to do it conveniently.
You would find having such a need in most Yii Projects. Your database needs a specific format to store date fields, while you may want to display it in different formats to the users on forms and other views.
Validators extending from CValidator all have a property named message. You can set this property in the corresponding validation rule to customize the error message. For example, the following validation rule uses an error message that is different from the default one:
Authentication and Authorization is a good tutorial. Among other topics, it describes basic aspects of Yii's RBAC implementation. But however hard I read the tutorial, I couldn't understand how exactly the hierarchy works. I found how to define authorization hierarchy, how business rules are evaluated, how to configure authManager, but almost nothing about how I should build my hierarchy, in what sequence its nodes are checked, when the checking process stops and what would be the checking result.