In a recent post to his blog, Gonzalo Ayuso shares a few tips on preventing SQL injection attacks on your applications.
Security is a part of our work as developers. We need to ensure our applications against malicious attacks. SQL Injection is one of the most common possible attacks. Basically SQL Injection is one kind of attack that happens when someone injects SQL statements in our application. You can find a lot of info about SQL Injection attack. Basically you need to follow the security golden rule: "Filter input, Escape output".
He advocates the use of the PDO abstraction layer to filter out a lot of the issues. Using its prepared statements, you can easily strip out things that just adding slashes to user input wouldn't prevent. He also includes a reminder about database permissions - allowing only certain users the ability to, for example, delete can help provide one more level of security (in other words, don't use a "super user" in production).