From: Date: July 7 1999 11:17am
Subject: MySQL 3.23 & autoincrement
List-Archive: http://lists.mysql.org/mysql/6726
Message-Id: <14211.6809.160007.598949@monty.pp.sci.fi>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

>>>>> "Barry" == Barry  <barry@stripped> writes:

Barry> Hello All,
Barry> I just downloaded the WinNT 3.22.24 and was looking through the new manual
Barry> at the Changes in 3.22.24 section. I came upon the following statement
Barry> about the MyISAM tables planned for 3.23.x.

Barry> "Internal handling of one AUTO_INCREMENT column. MyISAM will automatically
Barry> update this on INSERT/UPDATE. The AUTO_INCREMENT value can be reset with
Barry> myisamchk. This will make AUTO_INCREMENT columns faster and old numbers
Barry> will not be reused."

Barry> I am happy to see that old numbers will not be re-used, but am I
Barry> miss-reading this? Will an Update on an existing row modify the
Barry> Auto_Increment value? Using an Auto_Increment value as a static db record
Barry> identifier, I would not want this value to be modified once the row is
Barry> Inserted.

Hi!

The above means that if you do into an empty table:

INSERT INTO test (auto_column) values (NULL);
UPDATE test set auto_column=3 where auto_column=1;

MyISAM will notice that the next auto_increment it should use should
be 4.

MySQL will of course not change any existing value by it's own accord.

Regards,
Monty