I want to try and protect myself from my own stupidity. I have a number of sql databases, but one is LIVE. It is easy to drop tables but I want to set something (e.g. a password) which will help prevent me from dropping tables on the live database.
You could run 2 instances on that machine. Production databases on one, Test databases on the other.
But really LIVE stuff should be on a separate server to TEST/QA/DEV stuff. (Although we have "Staging-Test" on Production Servers so that we can properly evaluate performance in real-world conditions, so I'm not walking-my-talk)