Re: Expressing SQL in relational algebra
Date: Sat, 15 Mar 2003 01:20:27 -0500
"Neo" <neo55592_at_hotmail.com> wrote in message
> What might "SELECT * FROM T_Person WHERE (age=20) AND (weight=180);"
> look like if expressed in relational algreba? Any related links would
> be helpful. TIA.
That would depend on the notation. Assuming Years(n) and Pounds(m) are domain selectors for the domains of age and weight, I might write it as:
or in _The Third Manifesto_'s Tutorial D syntax:
T_Person WHERE ( age=Years(20) AND weight=Pounds(180) )
You will find many excellent references at: http://www.pgro.uk7.net/books.htm Received on Sat Mar 15 2003 - 07:20:27 CET