The key to becoming a competent white hat is knowing how the technology that you are trying to exploit actually works. SQL injection is one of the most common methods of attack used today and also one of the easiest to learn. In order to understand how this attack works, you need to have a solid grasp of ... you've guessed it ... SQL.
Web applications are becoming more and more popular, replacing traditional desktop programs at an accelerated rate. With all these new apps out on the web comes a variety of security implications associated with being connected to the internet where anyone can poke and prod at them. One of the simplest, yet most prevalent types of security flaws found in modern web apps is SQL injection.