Three modeling methodologies:
◦We all know the venerable Chen E-R models for database schemas; the extended E-R models (EER) incorporate inheritance
◦The object modeling approach uses UML class diagrams, somewhat similar to EER
◦The tables of the database define the “physical” schema, itself a model of underlying resources
The relationship between
these models involves schema mapping, covered in
last SIGMOD’s keynote talk by Phil
Bernstein[9]