If anyone can get to it, a sufficiently talented and dedicated professional can breach it. There is no such thing as absolute security for any application/database/whatnot that can be used. If you want data to be 100% secure, never store it!
Within reason, no one with the necessary talent will spend the necessary time to crack 99.99% of the systems in existance. Since it is FAR easier to use social engineering or a man-in-the-middle variant than brute force against almost every system that I've ever seen deployed, hard core "cracking" like what Jeorge Kabbi is describing is nearly un-necessary anymore.