I'm revisiting a principle I was taught 15 odd years ago and wondering
if it is still current - I've tried trawling through the ISO standards
and either its not defined as a standard or my searching wasn't good
enough! (probably the latter).

A company wants you to create a small application to help them track
sales orders. The orders will
arrive by phone or e-mail from a website, and a clerk will enter the
data into your application.

Recently a discussion came up in another thread about whether the term
"composite attribute" is acceptable and meaningful terminology.  I think
that other thread answered that question in the affirmative, to most
peoples' satisfaction.

I'm working with another client who creates a critical customer code
from data within the datamart.  This code is then fed back out to other
applications which, in turn, feed it back into the data warehouse.
I've always thought that the only appropriate applications development

Are there any (relational) schema standards for different kind of
business/enterprise areas? I am looking for and standardized way to
model an organization and other human resource related information like
employments, schedules etc.

Now that the "vs" thread has subsided I got to wondering how many
practitioners of database constraints as a key element of schema designs
consider there remains a need for further constraint (related) checking
in the application code itself?

I'm getting very interested in multiple reader/writer lock/lockless
locking issues with regard to data structures.
I'd like to find out what the state of the art is - in particular, with
regard to supporting multiple concurrent writers.

Looking at Darwen and Date's Third Manifesto, chapter four and
re-examining the fundamental operations that seem possible within the
relational model (to the extent that there is any common agreement about
what that is) I wonder how to answer the following question:

I have just started work at a new company as a 'Data Solutions
Architect', and am now patently aware why they need someone with Data
Architecture experience.
There databases (be they Oracle or SQL Server etc) have no constraints

I am tasked with designing a database for my company to track inventory
of different items we might sell.  We can't use any of the "shopping
carts" out there because this is really more for internal use and we
will be integrating it into our existing system later.

Codd said (something like) "relational valued (ie. non-atomic) values
in attributes not OK"
Date et. al. said: "Relational value attributes OK."
Codd said (something like) "NULLs OK"

Does anybody know how to represent
grouping queries in tuple relational
calculus? either that or an extension
that allows such operations ? (avg, sum,

I understand the Augmentation rule:
{ X -> Y } |= XZ -> YZ
but I don't understand why the rule can also be stated as:
{ X -> Y } |= XZ -> Y

I am currently looking for a piece of software that can do the
following, to lesser or greater degrees (this is quite general)...
- Can entity model/ produce logical & physical models etc
- Forward & Reverse engineer databases etc

I'm writing a database and i need help with the file strucure of the
database.
Can anyone analyse my file structure ??? Any ideas, suggestions etc. ?
I'm thinking in this format: