[Gnumed-devel] simplifying gmdrugs.sql

[Ian Haywood]

Two points:

- it appears that some drugs have more than ATC code, as they
have multiple therapeutic uses, I will look for some examples.

- the table drug_element is a kludge, but has a very important aspect.

In the old tables, classes and drugs where is separate tables. This meant
separate drug<->drug interaction and class<->class interaction tables,
as well as drug<->warning, class<->warning, drug<->side_effect,
class<->side_effect, and so on. Also, when you wanted to
link a drug and  a class together as an interaction you needed *another*
drug-and-class linktable for interactions. 

Separate class and drug tables can be emulated using views if required.

Ian