Could you give an example of a stupid mistake that could expose the database? SQL injection attacks are pretty hard to accidentally put into any reasonably well

Could you give an example of a stupid mistake that could expose the database? SQL injection attacks are pretty hard to accidentally put into any reasonably well-built system, so I'm curious if you know of any other mechanism through which you could entice a database dump out of a web application. I guess you could go after the OS or the web server, but I was under the impression you were talking about stupid mistakes from the web developer, not the developers of the OS or web server.