Re: Cannot step through asynchronous iterator manually

From	Michael Torrie <torriem@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: Cannot step through asynchronous iterator manually
Date	2016-01-30 12:42 -0700
Message-ID	<mailman.136.1454182970.2338.python-list@python.org> (permalink)
References	<n8hjmt$b8n$1@ger.gmane.org> <CALwzid=sSDSm8hdAN+ORJ54A_jEu9Wc8103iqGKAah8mrj-TXw@mail.gmail.com> <n8hrs1$orn$1@ger.gmane.org>

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On 01/30/2016 01:22 AM, Frank Millman wrote:
> There are times when I want to execute a SELECT statement, and test for 
> three possibilities -
>     - if no rows are returned, the object does not exist
>     - if one row is returned, the object does exist
>     - if more that one row is returned, raise an exception

Is there a reason you cannot get SQL to answer this question for you?
Something like:

SELECT count(some_field) WHERE condition

That will always return one row, with one field that will either be 0,
1, or more than 1.

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Re: Cannot step through asynchronous iterator manually Michael Torrie <torriem@gmail.com> - 2016-01-30 12:42 -0700

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