Re: Question on Structuring Product Attributes

Op maandag 11 februari 2013 09:05:46 UTC+1 schreef Derek Asirvadem het volgende:
> On Monday, 11 February 2013 11:38:51 UTC+11, James K. Lowden wrote:
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> > Except #6. ORDER BY, strictly speaking, returns a cursor, not a
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> > virtual table.
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> Let me assure that my platform Sybase does NOT use a cursor;

James said "returns", not "use".
A set is unordered, by definition. Hence, after applying ORDER BY, what is returned can not be a set. The ANSI standard calls it a cursor instead, which is a confusing term because a cursor is also the name of an SQL construction that appears to be mostly designed to give consultants an easy way to come in and play hero. Unfortunately, this overloaded term is what we are not stuck with.

How various vendors implement this is irrelevant in this group. (But I can assure you that you have been ill informed about the implementation details of MS SQL Server; I'll gladly provide more details if you want, but I'm not sure if that would be on-topic here).

> When would ORDER BY be relevant in a subquery (and therefore the prohinbition of it be relevant) ?

When combined with OFFSET and FETCH, or whatever other vendor-specific implementation of that functionality. Without it, it would indeed make no sense whatsoever.

Cheers,
Hugo Received on Mon Feb 11 2013 - 17:17:12 CET