Chapter 17. Object-orientation – A Data Modeler's Primer
The style of this chapter is intended to help a person with a relational background make the transition to OO thinking. We deliberately start with tables and columns, and bit of procedural code, and move little by little to the adoption of a few core OO ideas. The analogies may not be 100% precise, from an OO purist's point of view, but if they're helpful in building a bridge from the relational world view to that of object orientation, I suggest this more casual and friendly approach still has merit.
Encapsulation, or "They've hidden my data"
Let's assume we've got a relational table for employees95, and it's got columns such as Employee No for the employee's number, and Employee Name for ...