I was trying to avoid code duplication by making the generation of an sql insert command string common to the different tables.  I put this in the constructor so that it several inserts could be done without having to run this code over and over.

Since the sub classes that I ended up writing do not use the superclass, I think that I can change those subclasses into regular functions and change this insert command generator into another function, and get rid of the db_classes module altogether.