Re: Web dev, DB and "proper db design".

"Richard Quadling"  wrote in message 
news:CAKUjMCWJ4wiUO904OvYkS53Fsg4PPXa=qbOKcVHWFEmCpKpMMQ@mail.gmail.com...
>
>Hi.
>
>I've just had a conversation regarding DB, foreign keys and their benefits.
>
>I was told "I've never worked on a web application where foreign keys were
>used in the database".
>
>As someone who has spent 25 years working on accounting/epos systems on MS
>SQL Server (yep, windows) and now in a web environment and hearing the
>above, ... well, ... slightly concerned.
>
>So, in the biggest broadest terms, what do you lot do?
>
>DBs with no foreign keys (constrainted or not).
>ORM builders with manual definition of relationships between the tables.
>Inline SQL where you have to just remember all the relationships.
>Views for simple lookups? How do you handle updatable views (does mysql
>support them?)
>etc.
>
>Is there a difference in those in 'startups' and web only situations, or
>those doing more traditional development (split that as you like - I'm just
>trying to get an understanding and not go off on one!).
>
>No definitive answers, and I hope I get some wide experiences here.
>
>Thanks for looking.
>
>Richard.

There is a difference between having a field which is used as a foreign key 
and having a foreign key constraint defined in the database. Remember that 
foreign keys can be used in SELECT statements without there being a FK 
constraint. Constraints are only used in INSERT/UPDATE/DELETE operations, 
and never used for SELECTs

You cannot have relationships in a database without foreign keys, but you 
can have foreign keys with constraints.

-- 
Tony Marston

http://www.tonymarston.net
http://www.radicore.org