Image upload - how to create 2 uploads with different sizes

So what I need to do is create two uploads for products.
1 x big image
1 x small image

I need to store the name in the database so I can recall the path to display the image.
Or is there a way to call the main image from the database but add ‘small_’ onto the front of the path that is returned?
If not then I need to store in the database:
mainimage = big image path
inmagethumb = small image path.

Sorry for all the questions but I know there are some experts out there.