how to write this SQL query and SQL assertion


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Thread: how to write this SQL query and SQL assertion

  1. #1
    Diana Perkins Guest

    how to write this SQL query and SQL assertion


    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.

  2. #2
    Colin McGuigan Guest

    Re: how to write this SQL query and SQL assertion

    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




  3. #3
    Michael Levy Guest

    Re: how to write this SQL query and SQL assertion

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

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



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