RE: [PHP-DB] VARCHAR/CHAR question...
| From: | Anthony Martin | Date: | Fri, 08 Dec 2000 22:49:45 +0000 |
| Subject: | RE: [PHP-DB] VARCHAR/CHAR question... | ||
| Groups: | php.db | ||
| Request: | Send a blank email to php-db+get-5114@lists.php.net to get a copy of this message | ||
Although foreign keys don't mean anything in mySQL, it's still good practice
to make your PK/FK types match. For example:
CREATE TABLE ADDRESS (
ADDR_LN1 VARCHAR(30),
ADDR_LN2 VARCHAR(30),
CITY VARCHAR(30),
STATE_CD CHAR(2) /* no table wide advantage*/
) ;
CRATE TABLE STATE (
CD CHAR(2) /* table wide advantage */
) ;
What I don't know is if there's an advantage to the speed of the JOIN on the
STATE side.
Who knows, who cares?
Anthony
-----Original Message-----
From: Adv. Systems Design [mailto:asd_2000@yahoo.com]
Sent: Friday, December 08, 2000 1:01 PM
To: Michael Zornek; php-db@lists.php.net
Subject: Re: [PHP-DB] VARCHAR/CHAR question...
Michael:
this is correct...only with mysql...and the reason for
this is that any speed and storage advantages you may
have gained by specifying a field to be CHAR is lost
if in the same row you have another field of type
VARCHAR, so they both may as well be VARCHAR...
...it really makes little difference...in terms of
storage, if you really plan to have so many records
that this would be of consequence, you are probably
better off going with a databa$e like oracle...
That is the way I understand it anyways...
Luis
--- Michael Zornek <mzornek@seyboldreports.com> wrote:
> I'm new to PHP, and I found a questionable line in a
> book I'm reading
> (BEGINING PHP 4), in the MySQL chapter page 390 it
> says:
>
> " A final note on VARCHAR/CHAR type fields; if your
> table has at
> least one VARCHAR field all character fields are
> converted to VARCHAR
> type even if you define them otherwise."
>
> That doesn't seen fair or correct.
>
> Anybody have any comments or suggestions. I'll
> gladly follow this in
> designing my new DB but am suprised to read it.
>
> mike
>
>
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