Depending on the exact nature of your data, you're probably looking at a HoH (Hash of Hashes) or a HoL (Hash of Lists).
The PDSC gives a good introduction and overview of these.
As far as storing the data, apart from a database there are several other options, including a plain old text file. Storable might be a quick and easy solution.

It would be helpful if you could post a half-dozen lines of sample data from your CSV file.

Cheers,
Darren :)