Programming

I would also say, that if you have not heard of exploits you have not been listening. Ransomware has been in the news all the time. All security is porous and shit happens too. This is why a lot of companies have gone crazy nuts about IT security and other processes. There is a good reason.

I worked for a company that was migrating an enterprise system. They did the rollout by region, but at times regions could not ship product for a month or more. I saw from outside, but one has to wonder who thought that was acceptable or reasonable.

Bottom line in IT if it can happen it will. If it has not been tested assume it does not work, etc. Assume the worst because there are so many more way things can go wrong then work correctly.

It depends. A typical upgrade to software doesn't touch the database at all. The database doesn't change if you don't change it. Some updates will do migrations of databases to handle schema changes. There's specific technologies that aid in this process such as liquibase. Updates that are especially potentially volatile will sometimes involve making backups of the database just in case. But any sane company will have nightly backups if not better with a couple fallback options in case of issues.

Good database management will involve least access principals so nobody has access to those most dangerous commands and few people/systems have access to the merely quite dangerous commands.

The bigger you are, the more process and protections you put in place (ideally) to decrease the chance of such incidents and more importantly, have a Playbook defining what to do to quickly recover when they do happen. There will end up being one to seversl classes of employees between devs and the critical prod databases in big companies. Companies will pay millions in wages and vendor contracts for systems to provide observability and protection that covers database related incidents. And those protections will also include audits and change control processes for any code that runs.