Where to find product name in Prestashop Database structure

Question

i'm developing a very simple (for newbie user) back end for prestashop, and i would like to know where to find the product’s images name uploaded.. I know they are into “img/p” directory. But i don’t know: 1. In which database table they are .. linked 2. Why they are called (for example): 1-18-small.jpg … why “1-18” instead “1” (his productid) ? what that number means ?

Thanks