Is this possible to link the value to a database in Apple's iWork suite?
In any program to find out what fields/data can be inserted at a given point look for the menu item "Insert" if there is one you will see under that menu diffent types of data that can be inserted.  I pages you can "Insert" any of the information from the Addressbook.  In numbers it is much more limited.

AppleScript is most probley to best solution for other data and the apps you ask about.

Better app's for this sort of thing are OpenOffice and MS-Office.