Property sheets are tabbed dialog boxes containing pages that the user can switch with mouse clicks. They are a part of common library of windows just like dialog and other controls. E.g. when a user adds a schedules task it walks him through a wizard which is nothing but a property sheet. The functionality of property sheets is encapsulated in MFC classes of CPropertySheet and CPropertyPage. CPropertyPage represents a page in a property sheet and is a subclass of CDialog. Like dialog boxes property sheets can be modal or modeless. Use CPropertySheet::DoModal for modal and CPropertySheet::Create for a modeless property sheet.  There are four broad steps in creating a property page: 1. For each property page create a dialog template.   2. For the created dialog associate a class that derives from CPropertyPage.   3. Derive a property sheet class from CPropertySheet and create an object for each above created property pages.   4. Add the property page objects to the created property sheet using AddPage.   5. Call the doModal function of the property sheet to display it on the screen.

When you are designing a generic class to contain or otherwise manage objects of other types, when the format and behavior of those other types are unimportant to their containment or management, and particularly when those other types are unknown (thus, the genericity) to the designer of the container or manager class.

master-Controls the user database and SQL server as whole.model-Servers as a template used in creating new user database.msdb-Provides support for the SQL Server Executive. Tempdb-Stores temporary tables that disappear at the end of a session.

Its very simple to check whether user is logged in or not.
U can make a seperate page called session.php and called this file on every page even better is to make a template page where you once called this page it will be applicable to all pages which uses this template.
In that file you can check whether user is logged in or not by using session.