Обсуждение: Equivalence Rules

Hi
Which equivalence rule from those are listed in
email's attachment are implemented in postgresql?
where are them?
Thanks

Ali Piroozi wrote
> Hi
> Which equivalence rule from those are listed in
> email's attachment are implemented in postgresql?
> where are them?

What do you mean by "where"?

The various JOINS and UNION/INTERSECT/DIFFERENCE are all defined
capabilities.

SQL is not purely relational in nature so some of the mathematical rules may
not be exactly implemented as theory would dictate but largely they are
present.

I would suggesting providing more context as to why you are asking this as
people are more likely to provide help at this level of technical depth if
they know why; and can frame their answers more appropriately.

David J.





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<div dir="ltr"><div class="gmail_extra">"where" means, which function or which part of source code.</div><div
class="gmail_extra">Iwant to use that(function or part of source code), to produce the equivalence</div><div
class="gmail_extra">(basedon equivalence rules in attachment) Relational Algebra</div><div class="gmail_extra">for a
givenSQL query(Relational Algebra).</div></div>