Date manipulation and Java 'interface' equivalents

[Martin Christensen]

Howdy,

There are two matters for which I would like clarification.

First of all, I am doing some statistics with a PostgreSQL database,
and for this I need to manipulate some dates, ie. add a week to this
date or subtract a month from another. I didn't find any obvious
candidates for this kind of date math in the library reference. Now,
_of course_ this can be done in Python rather than forcing me to use
the DBMS for this, but... erm... how?

Second question: is there a Python equivalent of Java interfaces? In a
matter of months I'll be constructing a web based sales and customer
relations thingy, and a similar feature would really make things
easier. I haven't decided on the implementation language yet, but
this is one of the things that make Java more appealing.

Martin

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