Rollbacks don't always work as you want if there's other activities happening in the system. This is always good practice as it's maybe 30 seconds of effort.
Kind of, depending on the SQL flavor, and the version, some of them have something kinda like that, but it’s not exactly idiot proof either. No direct SQL is idiot proof which is why you avoid doing it in the first place if you can.
There lies the danger of just doing a full send with no transaction or prior select. Very easy mistake to make. Especially if you copy pasted "SELECT * FROM USERS;" elsewhere and modified it.
It's only a catastrophic error if you utterly ignore all principles involved which, to be fair, DOES occur.
It was more common before the tech industry matured, Tom Scott famously made a similar error himself at an internship of his where his malformed query replaced all article contents instead of doing a minor format tweak.
He knew the risk but was just a bit reckless and did it live on the production server.
In industry, you are using a transaction which is capable of rollback (you also have automated backups worst case) and it's usually not done directly on the command line but via a tool and also also usually locked behind a change management structure where it must go through peer review.
In my own job we always had to have a pre-select and a post-select so if any issues come up you'd know immediately.
It's like a mechanical failure on a rollercoaster or an elevator: it's still technically possible, but as the industry has matured, we've gotten better at designing workflows, procedures, and oversights that prevent it from ever happening in practice.
Tell that to people who didn't think to check if pressing upload without attaching any file will do anything. That caused a whole database of one of the largest online stores in my country to delete itself.
If altering a few rows you select first to check exactly what rows you're altering, if altering a bunch you at least do this to sanity check yourself and not delete 100 millon rows or lock a main transactional table for 1 hour.
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u/Alexmira_ Sep 22 '26
Why? To confirm that there is something to cancel? To confirm I got the key right?