[DB-SIG] Cursor.description when Cursor.rowcount == 0

Carsten Haese carsten at uniqsys.com
Fri Nov 10 19:30:48 CET 2006


On Fri, 2006-11-10 at 11:35 -0500, Art Protin wrote:
> not producing a result is 
> not the same as producing a table of
> zero rows by one or more columns.
> (This is like the distinction between 
> the two comparisons
>                     "" == False
> and
>                    "" is False
> , the empty string has the same 'value' as False while remaining distinct.)

By the way, neither of these comparisons is true. The empty string is
neither equal nor identical to False. Coercing the empty string into a
bool results in False, which equals, and is identical to, False.

A better analogy for what you're trying to say is the difference between
None and []. DML/DDL/DCL operations produce no result set, in the sense
of None. A DQL operation that doesn't return any rows produces an empty
result set, in the sense of [].

-Carsten




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