I cant find the meanings of different Relational Calnulus operators used
in TRC and DRC too. Cant understand the utility of Rel. Calculus at the
first place.

Help Any one Plz


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sibun wrote:


You might need to explain what TRC and DRC are before anyone can help
you. At least, they are not acronyms I'm familiar with.

Relational Calculus is an alternative to Relational Algebra, and is
equivalent to it. It is a way of asking questions of a database.


--
Jonathan Leffler #include <disclaimer.h>
Email: jleffler (AT) earthlink (DOT) net, jleffler (AT) us (DOT) ibm.com
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/

sibun wrote:
The operators in the tuple calculus and domain calculus are the usual
operators from first order logic (existential quantification, universal
quantification, and, or, not). What is it that you don't understand about
them?

The calculi are usually assumed to be more declarative then the algebra(s).
That means that you just specify the "what" and less the "how". That is a
good quality for a query language. Also (formal) reasoning for the calculi
is easier than the algebra.

-- Jan Hidders