What is mrDBC?  mrDBC is a set of classes which make it easy to
work with mySQL databases. The classes handle a main table with
an additional table containing optional attributes. This makes
it easy to add a new attribute without changing the table
structure.  Other features:    • can track create information
(user and time)   • can track modification information (user and
time)   • can cache objects if wished   • can lock objects for
the time of access. So actually these classes   • provide an
easy way to implement objects stored in databases   • make it
easy to extend the given functionality