Re: multiple current_timestamp

From: Jim Winstead <jimw(at)mysql.com>
Date: Sun Jul 29 2007 - 22:53:48 EDT

On Sun, Jul 29, 2007 at 07:02:19PM -0700, Eric Bergen wrote:
> That's a much better example. It does seem very strange that the
> timestamp functionality isn't more flexible. I suspect there are other
> things wrong in that area too. While playing around with timestamp
> definitions I found that the on update timestamp column still has to
> be listed before any other timestamps.
>
> I can't find anything in the manual that says the "magic" timestamp
> column still needs to be first like it was in 4.0.

It doesn't.

mysql> create table t1 (a timestamp default 0, b timestamp

    -> on update current_timestamp);
Query OK, 0 rows affected (0.01 sec)
mysql> show create table t1\G

*************************** 1. row ***************************
       Table: t1

Create Table: CREATE TABLE `t1` (
  `a` timestamp NOT NULL default '0000-00-00 00:00:00',   `b` timestamp NOT NULL default '0000-00-00 00:00:00' on update CURRENT_TIMESTAMP
) ENGINE=MyISAM DEFAULT CHARSET=latin1

I don't know if there is a strong technical reason for only allowing a single timestamp field to be automatically set or automatically updated, or the limitation was just a carry-over from when only the first timestamp field was auto-set/update. I wouldn't expect anyone at MySQL to jump at implementing this, but a patch would be looked at. (But since you can get the same effect with a trigger, it may not have a shot.)

Jim Winstead
MySQL Inc.

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Received on Sun Jul 29 22:54:04 2007