I have a table A with two fields, length and temperature, eg.
Both fields have some charateristics, like:

field length to use when printing,
units (meters, degrees)
maximum value
minimum value
default value
etc etc.

How would I describe such a situation in MySQL ?
I was thinking of making another table B of "characterisctics" and then
connecting fields in table A to records in table B.
Can that be done in MySQL ?

On Tue, 11 Dec 2007 11:08:00 +0100, Osiris <et57@hotmail.com> wrote:
> I have a table A with two fields, length and temperature, eg.
> Both fields have some charateristics, like:
>
> field length to use when printing,

Nothing to do with MySQL.

> units (meters, degrees)

Again, nothing to do with MySQL, or the value in the columns (just append
it if needed).

> maximum value
> minimum value

Unless you can whitelist all the values (foreign key constraint on another
field/table holding all possible values for the column, you'll have to use
triggers.

> default value

Default is easily given as a field property.

> How would I describe such a situation in MySQL ?
> I was thinking of making another table B of "characterisctics" and then
> connecting fields in table A to records in table B.
> Can that be done in MySQL ?

You can store some information about a field in another table. Most of
what I think you want cannot be done automatically with MySQL though,
you'll have to use the logic either in the script/application using MySQL,
or be prepared to write some very long queries, with dozens of
if-statemenst/joins for each field just to get the right 'representation'.

For more control over what goes into a field/row or gets deleted, you can
use triggers and/or foreign key constraints. There is no such thing for
selects though.
--
Rik Wasmus