"UPDATE table_name SET w = $1, x = $2, z = $4 WHERE y = $3 RETURNING *",
does not do the same as
"UPDATE table_name SET w = $1, x = $2, y = $3, z = $4 RETURNING *",
It’s 2 am and my mind blanked out the WHERE, and just wanted the numbers neatly in order of 1234.
idiot.
FML.
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
UPDATEorDELETEwithoutWHERE. Use it.I tried to find this setting for postgres and Ms SQLserver, the two databases I interact with. I wasn’t able to find any settings to that effect, do you happen to know them?
It’s supported in MySQL and MariaDB out of box:
https://dev.mysql.com/doc/refman/8.0/en/mysql-command-options.html#option_mysql_safe-updates
In Postgres there is an extension for it:
https://supabase.com/docs/guides/database/extensions/pg-safeupdate
for postgres and Ms SQLserver
It’s not really a SQL Language feature, more an IDE feature. So to tell you where the settings are, we’d have to know which IDE you’re using.
For example, in DataGrip (which I think you can use both for postgres and MSSQL), there’s “Show warning before running potentially unsafe queries”
If you forgot to put the WHERE clause in DELETE and UPDATE statements, DataGrip displays a notification to remind you about that. If you omitted the WHERE clause intentionally, you can execute current statements as you planned.
That would be SQL management studio and psql on the command line.
The best I could find was some plugins for SQL management studio (ssmsboost) and disable automatic commits for psql.
I didn’t mean this as IDE thing, there is an extension to postgres and server configuration for mysql/mardiadb. Posted the links above
–i-am-a-dummy 😂
I didn’t mean this as IDE thing
Well, the link you’ve posted is specifically for MySQL CLI Client - Maybe I should have I said “Client” instead of “IDE” - but if he uses a different IDE/Client besides MySQL-CLI it’s probably a different setting
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 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
WHO, WHAT,
WHERE, WHEN, WHY, HOWI learned this lesson too
This is a hard lesson to learn. From now on, my guess is you will have dozens of backups.
And a development environment. And not touch production without running the exact code at least once and being well slept.
Fuck that, get shit housed and still do it right. That’s a pro.
Replied hastily, but the way to run db statements in prod while dealing with sleep deprivation and drinking too much is to run it a bunch in several test env scenarios so you’re just copy pasting to prod and it CAN confidently be done. Also enable transactions and determine several, valid smoke tests.
Edit: a -> several
That’s not pro, that’s just reckless gambling.
Totally right! You must set yourself up so a fool can run in prod and produce the expected result. Which is the purpose of a test env.
I’ve read something like “there are two kinds of people: those who backup and those who are about to”
This is the way
And always use a transaction so you’re required to commit to make it permanent. See an unexpected result? Rollback.
Transactions aren’t backups. You can just as easily commit before fully realizing it. Backups, backups, backups.
Backups are for emergencies.
Transactions are for oopsies.
Yes, but
- Begin transaction
- Update table set x=‘oopsie’
- Sees 42096 rows affected
- Rollback
Can prevent a restore, whereas doing the update with auto commit guarantees a restore on (mostly) every error you make
Can prevent a restore, whereas doing the update with auto commit guarantees a restore on (mostly) every error you make
Exactly. Restores often result in system downtime and may take hours and involve lots of people. The backup might not have the latest data either, and restoring to a single table you screwed up may not be feasible or come with risk of inconsistent data being loaded. Even if you just created the backup before your statement, what about the transaction coming in while you’re working and after you realize your error? Can you restore without impacting those?
You want to avoid all of that if possible. If you’re mucking with data that you’ll have to restore if you mess up, production or not, you should be working with an open transaction. As you said… if you see an unexpected number of rows updated, easy to rollback. And you can run queries after you’ve modified the data to confirm your table contains data as you expect now. Something surprising… rollback and re-think what you’re doing. Better to never touch a backup and not shoot yourself in the foot and your data in the face all due to a stupid, easily preventable mistake.
Pro tip: transactions are your friend
They are - until you leave them open and go home…
Temporarily locked overnight >>> broken stuff in prod
This is the way.
Completely agree, transactions are amazing for this kind of thing. In a previous team we also had a policy of always pairing if you need to do any db surgery in prod so you have a second pair of eyes + rubber duck to explain what you’re doing.
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 addingwhere 1=1to the end of your SQL, it kind of defeats the purpose.MySQL (and by extension, MariaDB) has an even better option:
mysql --i-am-a-dummy
Amazing! These are going in my.conf ASAP.
Transactions help more, IMO. The 1=1 becomes a real habit.
Ctrl+z bro
Jk, sounds tough
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, zI get mildly mad all the time when writing SQL because I feel like it’s upside down
Instead of
select u.id. u.email, p.name from user u join persona p on p.user_id = u.id where u.active = truewhere the columns are referenced before they’re defined (like what is u.id? Keep reading to find out!)
it should instead be
from user u join persona p on u.id = p.user_id where u.active = true select u.id, u.email, p.nameNow nothing is defined before it’s used, and you’re less likely to miss your where clause. I usually write the joins first anyway because I know what tables I care about, but don’t know which specific things I’ll want.
I can’t think of any other languages that use things before they’re defined except extremely dysfunctional JavaScript.
From the cabinet, get a cup.
You might enjoy https://github.com/max-sixty/prql
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.
Because I’m relatively new at this type of thing, how does that appear on the front end? I’m using a js/html front end and a jsnode backend. Would I just see a popup before I make any changes?
If you’re asking about the information about the number of rows, oracle db clients do that. For nodejs, oracle’s library will provide this number in the response to a dml statement execution. So you can retrieve it in your backend code. You have to write additional code to bring this message to the front-end.
Awesome, thanks for the info. Definitely super useful for debug mode whilst I’m fixing and tampering!
No idea. My tools connect directly to the DB server, rather than going though any web server shenanigans.
Been there, done that, I hope you have a recent backup!
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.
I have done this too. Shit happens.
One of my co-workers used to write
UPDATEstatements backwards limit then where etc, to prevent this stuff, feels like a bit of a faff to me.I always write it as a select, before turning it into a delete or update. I have burned myself too often already.
Oh I did that like a year ago.
And then last night had an error that led me back near this code and stupidly thought “hey it’d look neater if those numbers were in order”
^ this is a very good tip that ive been using myself too
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.
deleted by creator
