how to write this SQL query and SQL assertion

[Diana Perkins]

Hi all:

I'm trying to write an SQL query and an SQL assertion for the following problem
for my database class. I've just started and am able to do some of the easier
problems but am having problems with this. If anyone could help me, it would
be greatly appreciated.

Thanks, Diana.

Given the database schema R(a, b, c), and a relation r on the schema R, write
an SQL query to test wheather the functional dependency b->c (b implies c)
holds on relation r. Also write an SQL assertion that enforces the functional
dependency. Assume that no null values are present.

[Colin McGuigan]

Diana Perkins <makavelius@aol.com> wrote in message
news:3a1a401a$1@news.devx.com...
>
> Hi all:
>
> I'm trying to write an SQL query and an SQL assertion for the following
problem
> for my database class. I've just started and am able to do some of the
easier
> problems but am having problems with this. If anyone could help me, it
would
> be greatly appreciated.
>
> Thanks, Diana.
>
> Given the database schema R(a, b, c), and a relation r on the schema R,
write
> an SQL query to test wheather the functional dependency b->c (b implies c)
> holds on relation r. Also write an SQL assertion that enforces the
functional
> dependency. Assume that no null values are present.

You know, I've been programming in SQL for years, and I have no clue what
this means. =P

--
Colin McGuigan

[Michael Levy]

Funny. I was thinking the same thing. What is a "SQL Assertion?" A
constraint?

-Mike
--
Michael Levy MCDBA, MCSD, MCT
michaell@gasullivan.com