... simple database access, oryou are creating middle-tier components to handle databaseaccess, understanding how to connect to a database, retrieveinformation, and manipulate data are critical to ... so far is that you can actually use the base class as a variable type, and you can handle any derived class with that new variable.For example, examine the following code. The Transportationclass ... Yet, both a Carand a Bikeclass might inherit from a base Transportationclass, which could also be usedas the basis for a Planeclass, a Trainclass, a HotAirBalloonclass, and so on.Polymorphism...