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SQL Design Patterns (2010)

(vadimtropashko.wordpress.com)
149 points mci | 3 comments | 27 Aug 25 04:59 UTC | HN request time: 0.612s | source
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potatoproduct ◴[30 Aug 25 19:11 UTC] No.45077193[source]▶
Not ashamed to admit that I never really thought about the distinct operator 'being redundant' as its essentially just a group by.
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1. paulddraper ◴[31 Aug 25 02:11 UTC] No.45079717[source]▶
SELECT DISTINCT is often a code smell. (Not always.) If you see it, there’s a 70% chance it got slapped on to fix an issue that should have been solved a different way.

SELECT DISTINCT ON is different, and useful.

replies(1): >>45081149 #
2. aspaviento ◴[31 Aug 25 07:29 UTC] No.45081149[source]▶
I had a teacher who had specific rules for exams when we wrote SQL statements:

- For a question worth 2 points, if you use the word "DISTINCT" when it wasn't needed, you lose 0.5 points.

- If you don't use "DISTINCT" when it was necessary, you lose all 2 points.

replies(1): >>45083817 #
3. 9dev ◴[31 Aug 25 15:15 UTC] No.45083817[source]▶
Oh yes, introducing a little game theory anxiety into exam questions sounds like a wonderful little torturing tool!