General programming advice on how to create a software with database

I have a little programming experience mainly using Borland C++ in the past. I am nowadays trying to create a software which mainly will do the following :

- The user will select a list of variables (e.g. symptoms of a disease)
- The software will list the possible disease according to the symptoms selected
- The software will suggest a proper therapy.

And this should go vice versa . (e.g. selecting a therapy , then the software will automatically list the diseases which can be treated with this therapy, or selecting a disease and then the software will automatically list the symptoms etc.)

My question is rather very general: What programming language (or database?) should I use / or what do I have to study in order to gain the proper knoweldge to build this software in the best way? Thanks a lot.