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Re: [PROGRAMMERING] [Database] Transaktioner med eller udenoptællingsfelt?



On Tue, 10 Aug 2004 20:57:49 +0000 (UTC)
Anders wrote:

> > Jeg har ikke hørt, at teorien skulle udtale sig om hvad en korrekt
> > fremgangsmåde er. Når jeg designer databaser bruger jeg altid et lille
> > ordsprog: "En mand med to ure, ved aldrig hvad klokken er". Så hvis du
> > kan beregne et felt ud fra et andet, så vil jeg undlade at medtage det
> > beregnelige felt i databasen. Ellers risikerer du en dag at stå i den
> > situation, hvor din database påstår en ting og din udregning påstår en
> > anden og så har du balladen ;-)
> 
> Det var da et umådeligt fornuftigt ordsprog, det vil jeg straks tage til
> mig, med den tilhørende visdom :)

Er der ikke i PostgreSQL funktionalitet til at vedligeholde
tæller-felter? Enten ved "user-defined functions" eller er der en
indbygget funktion for netop dette almindelige formål? Jeg har
ikke tid at slå op, desværre, men PostgreSQL er vældig godt
dokumenteret. Det er MySQL også.

Det er et performance spørgsmål. Hvis du skal gennemtrawle 100000
records for at tælle lager op, så tager det lidt længere tid;-)


-- 
donald_j_axel donax snabela get2net.dk -- http://d-axel.dk/


 
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