A12.1RMapHalpinTopcatHints.doc 

Consider the scenario :

"A student owns a computer and, a student uses a computer at home. "

1. Write out the elementary facts

2. Write out the topcats associated with each phrase embedded within each elementary fact ( don't forget the overall topcats)!

3. Draw the Halpin ORM diagrams for your elementary facts. 

4. Draw the topcat diagrams for your elementary facts.

5. Write the table schema for the Halpin diagram ( why did you give your table  that name? :-) 

6. Write the table schema for the Topcat diagram. ( Note, does the overall topcat help to name your tables)?

Data use case to populate the tables ( P1, P2 are brands of PCs while Mac is the generic term for a Mac) 

Ann uses a P2

Fred uses a P2, a Mac, and owns a P2

Sue uses a P2 and owns a P1

 

Tom owns a Mac

Mary uses a Mac and a P1

7. Insert this data in your ORM tables only 

8. Perform a natural join on your ORM tables to determine who both owns and uses a PC.