From my own personal experience, finding accurate information regarding SQL injection, and even basic PHP security, is actually quite difficult for the novice. A search on Google can bring the best of tutorials and the worst of home-made blog posts. For the rookie, it all seems to work.
I think if we could offer these guys a good resource that stays up-to-date and offers multiple scenarios, we would find less of these questions. I'm sure that each question's author thinks that because their database scheme is "unique", a new SQL injection question is necessary. A thorough read that contained a generalized form of each best practice revolving around the SQL injection/PDO/MySQL/database access layer world would be great.
I agree with 200_success here, and we should encourage these questions and teach them, instead of closing their minds. Before they post though, if they could see some modern standards and current security trends, then we would be in better shape!