I have 2 tables, "sims" (as in mobile phone sim cards) and "phones" (as
in mobile phones).  I can add any number of sim cards to the "sims"
table and any number of mobile phones to the "phones" table.  Simple enough.
Rule 1: A sim card can either be in a phone, or not in a phone.  ...

As the subject says...
The traditional direct image system approach consists of having
relations constraints implemented at the time when the relation is
updated meaning during UPDATE/DELETE/INSERT operations.  As a part of

i'm nearly ready for my first release of my new concurrent, multi-
threaded, ACID transactional, logical idempotent logging, lock-free
database engine (key/value storage).
OK, enough buzzwords for today :)

Lately, I stumbled about the problem of how constraints are to be
implemented in the case of relations runtime-only (I call them virtual
- they can *roughly* be assimilated to functions/views)
representations.  I thought that it is necessity for a TRDBMS to allow

I want to make an array of RGB colors. For the set ( 0, 64, 128, 192,
255 ), I want to have each combination thereof ( the Cartesian
product? ) .
This is the query I have to do it:

While working on aggregation within groupping operations on the db
core I design for relation  manipulation, I questionned myself about
the opportunity of using new operators to simplify relational division
formulation and make it more systematic.   For instance, conside the

In another thread, I suggested that prefixing every tuple with an
auto-generated field (column) called ID amounted to reference by location
rather than reference by content.  Some people correctly point out to me
that there is a level of indirection gained by using ID fields ...

Speaking of illiteracy, here's a quote of a quote that's funnier than
anything I could come up with.  It's from Date's latest about sql and
relational theory at google books.  I'd say whoever wrote it manages to
offend SQL lovers, relational theorists and grade-school

I wondered if the DEFAULT clause along with the NOT NULL, PRIMARY KEY
clauses in a CREATE TABLE statement was a constraint.
Is it?
I think it's not. Anywhere google takes me seems to be involving SQL

Informally I think of abstract identifiers as "internal glue" within a
relational database.  A bit more formally, they are characterised as
identifiers that could be mapped bijectively to different values
throughout the database without changing the recorded information.

A couple of books I found interesting in the last couple of years
because they try to bridge the subjects were one by a guy named Toon
Kooplars, which I've lost at the moment and this one by Date.  It seems
that google books has some or all of it at

I am amit jain. I am fesing problem in diplay information in binary
tree. Actually I want to diaplay Agent List in bainary tree view and
access Agent List from mysql database.. please help me i do not know
how i can make binary tree in jsp.

How does one implement row-level security?
For instance, say you have an internal database for billing. You have
a table Clients, a child table Invoices related by client_id to
Clients.id, and a child LineItems related to Invoices.id by