Contains methods to get a connection to the database.
The database could be MS Access or MySQL
This class contains database specific code to connect to the database Access or MySQL
Only one instance of this class should ideally be used throughtout your application.
For demo purpose, we have kept the default constructor available to all classes.
Ideally you would override the default constructor and write a getInstance method which will
return a single DBConnection instance always,thus making it a singleton class.
In the current application,InitServlet instantiates this class and sets all the
variables like dbName,accessDBPath & mySQLDSN and puts that instance in the application context
so that it is available to all the jsps.