If you need a college professor to tell you "Check that the resource is owned by the logged in user requesting a change before you change it", you might never,

If you need a college professor to tell you "Check that the resource is owned by the logged in user requesting a change before you change it", you might never, ever be a good programmer no matter what. This was apparent to me when I'd been doing PHP for like 6 months. These issues are common sense.