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From:emierzwa Date:April 26 2005 4:58pm
Subject:RE: why NOT NULL in PRIMARY key??
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Martin, Shawn, you are correct. An oversight on my part...this is why I
still follow this list, I am always able to learn something and never
cease to be humbled.

Ed

-----Original Message-----
From: Martijn Tonies [mailto:m.tonies@stripped] 
Sent: Tuesday, April 26, 2005 8:01 AM
To: emierzwa; mysql@stripped
Subject: Re: why NOT NULL in PRIMARY key??



> Not every DBMS...
>
> MSSQL:
> Create Unique Index
> Microsoft(r) SQL Server(tm) checks for duplicate values when the index
> is created (if data already exists) and checks each time data is added
> with an INSERT or UPDATE statement. If duplicate key values exist, the
> CREATE INDEX statement is canceled and an error message giving the
first
> duplicate is returned. Multiple NULL values are considered duplicates
> when UNIQUE index is created.
>
>
> SYBASE:
> Create Unique Index
> Prohibits duplicate index (also called key) values. The system checks
> for duplicate key values when the index is created (if data already
> exists), and checks each time data is added with an insert or update.
If
> there is a duplicate key value or if more than one row contains a null
> value, the command is aborted and an error message giving the
duplicate
> is printed.

An unique index is not a primary key constraint.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS
SQL
Server
Upscene Productions
http://www.upscene.com

Thread
why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies26 Apr
  • Re: why NOT NULL in PRIMARY key??Jochem van Dieten26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
  • Re: why NOT NULL in PRIMARY key??Harald Fuchs26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??SGreen26 Apr
      • Att. Shawn GreenJigal van Hemert2 May
  • Re: why NOT NULL in PRIMARY key??Dawid Kuroczko26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??Jochem van Dieten26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??Paul DuBois26 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies26 Apr
  • Re: why NOT NULL in PRIMARY key??Mikhail Entaltsev26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
  • Re: why NOT NULL in PRIMARY key??Harald Fuchs26 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert27 Apr
    • Re: why NOT NULL in PRIMARY key??Peter Brawley27 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert27 Apr
    • Re: why NOT NULL in PRIMARY key??Frank Bax27 Apr
    • Re: why NOT NULL in PRIMARY key??Peter Brawley27 Apr
    • Re: why NOT NULL in PRIMARY key??Joerg Bruehe27 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert28 Apr
RE: why NOT NULL in PRIMARY key??Jay Blanchard26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??Paul DuBois26 Apr
  • RE: why NOT NULL in PRIMARY key??Frank Bax26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??Paul DuBois26 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies26 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert26 Apr
    • Re: why NOT NULL in PRIMARY key??Paul DuBois26 Apr
    • Re: why NOT NULL in PRIMARY key??Peter Brawley26 Apr
RE: why NOT NULL in PRIMARY key??emierzwa26 Apr
  • RE: why NOT NULL in PRIMARY key??SGreen26 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies26 Apr
RE: why NOT NULL in PRIMARY key??Jay Blanchard26 Apr
  • Re: why NOT NULL in PRIMARY key??Dawid Kuroczko27 Apr
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies27 Apr
RE: why NOT NULL in PRIMARY key??emierzwa26 Apr
Re: why NOT NULL in PRIMARY key??beacker30 Apr
  • Re: why NOT NULL in PRIMARY key??Jigal van Hemert1 May
  • Re: why NOT NULL in PRIMARY key??Martijn Tonies1 May