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#1 (**permalink**) 04-29-2008, 08:27 PM

Hi.

I've got a table with some fields, which I created with VARCHAR(100).

I want to optimize this table, and I want to modify the length of these
fields from VARCHAR(100) to VARCHAR(maximum_length), where "maximum_length"
is the length of the record with the longest field.

I could create a Perl script to do it, but I wonder if there's a mySQL
command which does it automatically.

Thank you very much,
--Charles

#2 (**permalink**) 04-29-2008, 08:27 PM

Hi Charles,

to get max . # characters:
SELECT MAX(CHAR_LENGTH(<fieldname>)) AS `MaxChars`;

to get max. # bytes:
SELECT MAX(LENGTH(<fieldname>)) AS `MaxBytes`;

HTH, Cor

----- Original Message -----
From: "Charles Lambach" <charles.lambach@gmail.com>
To: <mysql@lists.mysql.com>
Sent: Tuesday, April 29, 2008 1:21 PM
Subject: How to know the maximum length of a field

> Hi.
>
> I've got a table with some fields, which I created with VARCHAR(100).
>
> I want to optimize this table, and I want to modify the length of these
> fields from VARCHAR(100) to VARCHAR(maximum_length), where
> "maximum_length"
> is the length of the record with the longest field.
>
> I could create a Perl script to do it, but I wonder if there's a mySQL
> command which does it automatically.
>
> Thank you very much,
> --Charles
>

#3 (**permalink**) 04-29-2008, 08:27 PM

On Tuesday 29 April 2008 08:21:37 Charles Lambach wrote:
> Hi.
>
> I've got a table with some fields, which I created with VARCHAR(100).
>
> I want to optimize this table, and I want to modify the length of these
> fields from VARCHAR(100) to VARCHAR(maximum_length), where "maximum_length"
> is the length of the record with the longest field.
>
> I could create a Perl script to do it, but I wonder if there's a mySQL
> command which does it automatically.
>
> Thank you very much,
> --Charles

Couldn't you also use procedure analyse()?

SELECT column FROM table PROCEDURE ANALYSE(10, 2000);

kabel

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