It came to my head to make this one when I did half of the SQL injections on vulnerable boxes with SQLMap. A very good tool indeed, but it felt kind of empty not knowing anything about what's going on. So I started learning myself, and now here I am, explaining bit by bit of what I know till now.
Enjoy.
A practical approach within a vulnerable box, that's not made by me is coming next on #Kioptrix3 VM
;--+