Re: Expressing SQL in relational algebra

"Neo" <neo55592_at_hotmail.com> wrote in message <news:4b45d3ad.0304092013.507b9b8e_at_posting.google.com>...

> While the "T_" prefix does not make much sense in context of the
> simple discussion at hand, it is just an arbitrary convention I have
> used to help distinguish things in larger VB projects that interfaced
> to Tables, Queries, Forms, Macro, Modules, etc. The "T_", "F_", "Q_",
> "Mc_", "M_" prefixes served a function similar to that of the data
> type prefixes for variable names such as p for pointer, h for handle,
> i for integer, chk for checkbox, cbo for combo box, etc. See chapter
> 9, Power of Data Names, in "Code Complete" by Steve McConnell,
> Microsoft Press, ISBN 1-55615-484-4 for a discussion of the advantages
> of naming conventions.

...which would be irrelevant if, say, the IDE could tell you the type and scope of an identifier when you hover the cursor over it. (After all, "Quick Info" does seem to be too strenuous for some people...) Why pine for the dark days of editing code in NOTEPAD.EXE or "ed"?

However, relational algebra does have one advantage over the relational calculus -- the full relational calculus allows querying for sets that cannot be realized, such as a set of all real numbers not in A, or some such. SQL, originally intended as an /end-user/ query language, (har!) is a mish-mash of things from both the relational algebra and calculus and probably should be put out of our misery ASAP. (Thanks loads, IBM)

--
Joe Foster <mailto:jlfoster%40znet.com>   Space Cooties! <http://www.xenu.net/>
WARNING: I cannot be held responsible for the above        They're   coming  to
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