Posted by Jerry Stuckle on 05/15/06 14:20

Kenneth Downs wrote:
> Jerry Stuckle wrote:
>
>
>>Kenneth Downs wrote:
>>
>>>Bent Stigsen wrote:
>>>
>>>
>>>
>>>>The answer is D, implementing two tables.
>>>>One table with the characteristics, and one table containing two foreign
>>>>keys making the association between characteristics and the "items" (what
>>>>that might be).
>>>
>>>
>>>Anybody working with databases must have a reasonable method for altering
>>>table structures as a regular event and a reasonable way to synchronize
>>>structures and the code that works with them. Not having this will cost,
>>>and all solutions that seek to re-invent physical implementation produce
>>>burdens worse than the disease.
>>>
>>
>>I disagree. If you properly plan your installation, you will not need to
>>change
>>your tables. Over the years I've designed hundreds of databases; most of
>>them have never been changed.
>
>
> Sorry to hear that.
>

My customers aren't. It's because the databases were designed properly in the
first place.

>
>>Having to alter a database layout either means you've had a significant
>>change in the database needs, or, more likely, you didn't design it
>>properly in the first place.
>
>
> Or your customer loved it, their business is growing, and they've got more
> stuff for you to do.
>

And if it had been designed properly in the first place, you would have planned
for the growth.

You can't plan for all possible changes. But a good designer can plan ahead for
most of the potential changes and incorporate them in the database early.

A good DBA plans ahead. Those who say you should plan on changing your database
either don't plan ahead or, more likely, are just hackers throwing together code
to fix the current problem.

For instance - try a database with over 75 tables, all interrelated and linked
with foreign keys. Over 500K LOC working with this database. Changing a table,
even to add a column, is NOT necessarily a minor change. Lots for code to check
through.

And adding a new table can really cause problems. This is one successful
project I managed several years ago.

Even in my web sites I need to change virtually none of my database structures
after they've gone live - because I've planned ahead.

> Cheers,
>


--
==================
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

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