RE: Doohickey to visually show relationships between files

["Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>]

>Of course, there'd better be a good reason to have the relationships,
and 
>to set up RI constraints in the first place.  

In a new database I think I'd always have them. I like the idea of the
database protecting itself. Constrains, triggers, DRI, they all help me
ensure that I don't have an order for item 12345 when I don't have an
item 12345. Having the relationships in the DB also helps the power
users that access the data (Read-only) with query tools. Most modern
query tools can read the schema and help users link tables.

Of course, in an existing database, well... That's a different story.
Ever write an order header after your written the order details so you
can include summary information on the header? Boom. Or use customer
number zero to represent an unknown customer, boom. The lack of "nice"
null support makes life tougher too.

However, in either case, it can be nice to add the relations into the
ERD, even if you don't generate the DDL necessary to implement them. I
love having a ERD printed and hanging on the wall, makes it soooo much
easier to see the big picture. I've had ERDs that were 10x10 feet at
times (lots of 8x11 pages and tape <G>)

At times I'll also put them together for the "subsystem" I'm working on.
Again, I _can_ remember all the relationships, but why bother when I can
look at my wall and see the 6-10 tables I'm working with and how the
relate to each other.

-Walden

------------
Walden H Leverich III
President & CEO
Tech Software
(516) 627-3800 x11
WaldenL@xxxxxxxxxxxxxxx
http://www.TechSoftInc.com 

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)