Re: Eliminering af dubletter [mysql]

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Article #15184

#15184

From: Hroi Sigurdsson
Date: Fri, 06 Jul 2001 09:30

33 lines
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RipCord wrote:

> Jeg her en tabel med 5 kolonner (IDprimary, a, b, c, d)
> Er der nogen der kan komme i tanke om en simpel m�de at s�rge for at
> der ingen dubletter er, hvis man ser bort fra Prim�rn�glen, dvs.
> noget med distinctrow(a, b, c, d)

UNIQUE contraint, ala:

CREATE TABLE mytable (
	id INT NOT NULL PRIMARY KEY,
	a INT NOT NULL,
	b TEXT NOT NULL,
	c DATE NOT NULL,
	d CHAR(2) NOT NULL,
	UNIQUE(a, b, c, d)
)

I ovenst�ende eksempel skal a, b, c ,d tilsammen v�re unikke.

CREATE TABLE mytable (
	id INT NOT NULL PRIMARY KEY,
	a INT NOT NULL UNIQUE,
	b TEXT NOT NULL UNIQUE,
	c DATE NOT NULL UNIQUE,
	d CHAR(2) NOT NULL UNIQUE
)

Her skal hvert felt is�r v�re unik (sikkert ikke det du vil).

-- 
Hroi Sigurdsson                             hroi@netgroup.dk
Netgroup A/S                          http://www.netgroup.dk

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From: Hroi Sigurdsson <hroi@netgroup.dk>
Newsgroups: dk.edb.database
Subject: Re: Eliminering af dubletter [mysql]
Date: Fri, 06 Jul 2001 11:30:02 +0200
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