Re: Section 4.1.2.7 contains false information

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От David G. Johnston
Тема Re: Section 4.1.2.7 contains false information
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Msg-id CAKFQuwYXhvhr8hWd1ZjWedediHiC2pY4SrvOwSNDVu8sguBhdQ@mail.gmail.com
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Ответ на RE: Section 4.1.2.7 contains false information  (Jind?ich Vavru?ka <jindrich@vavruska.cz>)
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On Tue, Apr 9, 2019 at 3:03 PM Jind?ich Vavru?ka <jindrich@vavruska.cz> wrote:

Dear Tom, it works only in psql, it does not work when you talk to the server using postgresql protocol. That is my point.

e.g. in the following code the query causes Syntax error (see the text in red). That means it does not work. Interestingly, when I use $4::timestamp or CAST ( $4 as TIMESTAMP ) the syntax error does not occur.

 

        "INSERT INTO public.contest (contest_id, period_id, contest_name, start_ts, end_ts, default_format, status ) "

        + "VALUES ($1, $2, $3, TIMESTAMP $4, TIMESTAMP $5, $6, 'NEW' ) RETURNING contest_key",


And further on in that section its plainly states:

"To avoid syntactic ambiguity, the type 'string' syntax can only be used to specify the type of a simple literal constant."

Since what you've provided is not a simple literal constant it is expected to not work - and that either :: or cast() needs to be used instead.

If you'd like to make a concrete documentation suggestion please do so.  Given the scarcity of complaints seen here, and the fact that not everything can and should be documented everywhere, I'm not presently seeing an issue large enough to change the status quo.  Especially since its sounds more like you didn't read the section the explicitly covers the limitations of typename 'literal' and the universality of actual casting syntax (either SQL standard CAST or PostgreSQL double-colon).

There is indeed a lot of material here and sometime a quick question on the email lists is more efficient a learning mechanism than trying to get the documentation perfect.  This seems like one of those times.

David J.

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