I accidentally removed the WHERE clause from my SQL query in a personal tool. Every row is now the same. I overwrote 206,000+ rows. I have no backup, I am stupid.

This is a hard lesson to learn. From now on, my guess is you will have dozens of backups.

This doesn’t help you but may help others. I always run my updates and deletes as selects first, validate the results are what I want including their number and then change the select to delete, update, whatever

Pro tip: transactions are your friend

Postgres has a useful extension, pg_safeupdate

https://github.com/eradman/pg-safeupdate

It helps reduce these possibilities by requiring a where clause for updates or deletes.
I guess if you get into a habit of adding where 1=1 to the end of your SQL, it kind of defeats the purpose.

All (doesn't seem like MsSQL supports it, I thought that's a pretty basic feature) databases have special configuration that warn or throw error when you try to UPDATE or DELETE without WHERE. Use it.

You're not the first. You won't be the last. I'm just glad my DB of choice uses transactions by default, so I can see "rows updated: 3,258,123" and back the fuck out of it.

I genuinely believe that UPDATE and DELETE without a WHERE clause should be considered a syntax error. If you want to do all rows for some reason, it should have been something like UPDATE table SET field=value ALL.

this folks, is why you don't raw dog sql like some caveman

Always SELECT first. No exceptions.

I once dropped a table in a production database.

I never should have had write permissions on that database. You can bet they changed that when clinicians had to redo four days of work because the hosting company or whatever only had weekly backups, not daily.

So, I feel your pain.

You all run queries against production from your local? Insanity.

There is still the journal you could use to recover the old state of your database. I assume you commited after your update query, thus you would need to copy first the journal, remove the updates from it, and reconstruct the db from the altered journal.

This might be harder than what I'm saying and heavily depends on which db you used, but if it was a transactional one it has to have a journal (not sure about nosql ones).

Periodic, versioned backups are the ultimate defense against bugs.

WHO, WHAT, WHERE, WHEN, WHY, HOW

who thought it was a good idea to make the where condition in SQL syntax only correct after the set?? disaster waiting to happen

There was a time I worked as a third party for one of the 10 most accessed websites in my country. I got assigned to a project that has been maintained by another third party for 10+ years with no oversight. I have many stories from there but today's is that this company had very strict access control to the production database.

Third parties couldn't access the database directly. All fine and good, except for the fact that we were expected to setup some stuff in the database pretty much every week. The dude who kept this project running for the previous decade, unable to get proper credentials to do his job, instead created an input box in some system that allowed him to run any sql code.

You can already guess the rest of the story, right? For security reasons we had to do things in the least secure way imaginable. Eventually, wheres were forgotten.

I watched someone make this mistake during a screen share, she hit execute and I screamed "wait! You forgot the where!" Fortunately, it was such a huge database that SQL spun for a moment I guess deciding how it was going to do it before actually doing it, she was able to cancel it and ran a couple checks to confirm it hadn't actually changed anything yet. I don't think anything computer related has ever gotten my adrenaline going like that before or since

I did that once when I moved from one DB IDE to another and didn't realise the new one only ran the highlighted part of the query.

there were thousands of medical students going through a long process to find placements with doctors and we had a database and custom state machine to move them through the stages of application and approval.

a bug meant a student had been moved to the wrong state. so I used a snippet of SQL to reset that one student, and as a nervous habit highlighted parts of the query as I reread them to be sure it was correct.

then hit run with the first half highlighted, without the where clause, so everyone in the entire database got moved to the wrong fucking state.

we had 24 hourly backups but I did it late in the evening, and because it was a couple of days before the hard deadline for the students to get their placements done hundreds of students had been updating information that day.

I spent until 4am the next day working out ways to imply what state everyone was in by which other fields had been updated to what, and incidentally found the original bug in the process 😒

anyway, I hope you feel better soon buddy. it sucks but it happens, and not just to you. good luck.

In MSSQL, you can do a BEGIN TRAN before your UPDATE statement.

Then if the number of affected rows is not about what you'd expect, doing a ROLLBACK would undo the changes.

If the number of affected rows did look about right, doing a COMMIT would make the changes permanent.

Thanks for sharing your painfull lesson. I don't directly query DB's a lot, but WHEN I do in the future I'll select first and validate.. Such things can happen so fast. No self hate, man!

I have done this too. Shit happens.

One of my co-workers used to write UPDATE statements backwards limit then where etc, to prevent this stuff, feels like a bit of a faff to me.

Depending on the database used, the data might still be there, just really hard to recover (as in, its presence is a side-effect, not the intent).

https://stackoverflow.com/a/12472582 takes a look at Postgres case, for example.

you could use dbeaver that warns you for update and delete queries without a where clause, independently of the db system. I hope the functionality it's still there since, for totally unrelated motivations, I always use a where clause, even when buying groceries.

I learned the hard way about the beauty of backups and the 3, 2, 1 rule. And snapshots are the GOAT.

Even large and (supposedly) sophisticated teams can make this mistake, so dont feel bad. It’s all part of learning and growth. You have learned the lesson in a very real and visceral way - it will stick with you forever.

Example - a very large customer running our product across multiple servers, talking back to a large central (and shared) DB server. DB server shat itself. They called us up to see if we had any logs that could be used to reconstruct our part of their database server, because it turned out they had no backups. Had to say no.

Unrelated, but use placeholders instead of interpolation right into the query.

See: Little Bobby Tables. https://xkcd.com/327/

A gut wrenching mistake, hopefully you'll only make it once!

This is about the one thing where SQL is a badly designed language, and you should use a frontend that forces you to write your queries in the order (table, filter, columns) for consistency.

UPDATE table_name WHERE y = $3 SET w = $1, x = $2, z = $4 RETURNING *
FROM table_name SELECT w, x, y, z

Oof. Been there, done that, 0 stars; would not recommend.

Pressing F to pay respects. R.I.P. in pieces

Depending on how mission critical your data is...Set up delayed replicas and backups (and test that your backups can actually be restored from). Get a second pair of eyeballs on your query. Set up test environments and run it there before running it in production. The more automated testing you put into your pipeline, the better. Every edit should be committed and tested. (Kubernetes and GitLab Auto DevOps makes this kind of thing a cinch, every branch has a new test environment set up automatically)

Don't beat yourself up too much though. It happens even to seasoned pros.

I don't know if it makes you feel better but Tom Scott had a similar experience: https://youtu.be/X6NJkWbM1xk

Things like this make me glad I can only query my db.

If it's Microsoft SQL you should be able to replay the transaction log. But you should be doing something like daily full backups and hourly incremental or differential backups to avoid this situation in the first place.

SQL scouts credo: I will never use indexes, I will always use column names.

Ctrl+z bro

Jk, sounds tough

I learned this lesson too

I‘m using DataGrip (IntelliJ) for any manual SQL tomfoolery. I have been where you are. Luckily for me, the tool asks for additional confirmation when doing any update/delete without where clause.

Also, backups are a must, for all the right reasons and for any project.

Been there, done that, I hope you have a recent backup!