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Re: [PROGRAMMERING] [SQL] group by hjælp



Den Sat, 02 Jun 2007 23:09:14 +0200 skrev Kim Schulz:
>> Og heller ikke i postgresql.. som sagt .. en bug i mysql.
>> 
>> 
> NEJ! en alternativ implementation. Ifølge de seneste  SQL standarder
> (både ISO og ANSI) er der ikke mere krav om at alle SELECT kolonner er
> aggregerede

Jo, med mindre DBMSet implementerer den valgfri "functional dependencies" 
feature (T301). Og det kender jeg ikke til, at MySQL skulle implementere; 
i hvertfald kender jeg ikke til, at MySQL skulle tjekke funktionelle 
afhængigheder såfremt man undlader ikke-aggregerede elementer i sin 
SELECT-liste.

På http://rpbouman.blogspot.com/2007/05/debunking-group-by-myths.html kan 
man læse lidt om sagen. Men jeg synes, at nævnte artikel misbruger 
SQL:1999 (og senere)'s mulighed for mere "liberal" GROUP BY til at 
blåstemple MySQL's GROUP BY fortolkning, som jeg altså ikke finder gyldig.

-- 
Regards,
Troels Arvin <sslug@sslug>
http://troels.arvin.dk/


 
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