←back to thread

Sampling with SQL

(blog.moertel.com)
175 points thunderbong | 1 comments | 20 Oct 24 10:58 UTC | HN request time: 0.453s | source
Show context
emmelaich ◴[20 Oct 24 22:46 UTC] No.41899108[source]▶
Is there something in the SQL standard that says functions are guaranteed to executed more than once?

I swear that once I used something like random() and it was only executed once, making it useless for the task at hand. I had to use some trick to ensure it was executed for each row.

I may have used it in the `select` part. Dialect was Oracle's, from memory.

related: https://xkcd.com/221/

replies(5): >>41899141 #>>41899381 #>>41900027 #>>41901762 #>>41903922 #
1. magicalhippo ◴[21 Oct 24 08:02 UTC] No.41901762[source]▶
Conversely, today() and friends might be evaluated per row and not per row, to the mild surprise of some of us.

Just reinforced my belief of not assuming you know what the DB server is doing, verify!