Data validation is important for any application, and particularly so for database ones. There are a number of approaches to presenting information to a user, from list boxes to combo boxes, but sometimes these may be difficult to understand.

The Tree View Object is one of the approaches to this puzzle, and often times it's a very effective one. It uses the Windows Explorer metaphor to present information in a clear and intuitive way, while in the bargain provides entry validation almost for free.

This Tree View object can go three levels deep, either from a load or through cascaded TQuery objects. It has a number of properties to control the information display, node generation and selected value returns (often primary keys or identities).