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Sampling with SQL

(blog.moertel.com)
175 points thunderbong | 1 comments | 20 Oct 24 10:58 UTC | HN request time: 0.001s | source
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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/

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1. adornKey ◴[21 Oct 24 13:25 UTC] No.41903922[source]▶
About a decade ago I tried to use random() and I found its behaviour to be very random... The changelogs of all databases I used later contained bug fixes on this subject. (Sybase, Microsoft)

I'm not sure if standards today are consistent and trustworthy on this subject. Back in the day it was very obvious that most likely nobody ever seriously had tried to use random().