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From: Tom Lane <[email protected]>
To: Dagfinn Ilmari Mannsåker <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Artur Formella <[email protected]>
Cc: [email protected]
Subject: Re: Allowing additional commas between columns, and at the end of the SELECT clause
Date: Mon, 13 May 2024 10:11:34 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<CAEze2WhL_A9QO1xHQnEoYN1g5wsigqrL2+FLELcjFwaA-nP-Ug@mail.gmail.com>
	<[email protected]>

=?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <[email protected]> writes:
> Matthias van de Meent <[email protected]> writes:
>> Single trailing commas are a feature that's more and more common in
>> languages, yes, but arbitrary excess commas is new to me. Could you
>> provide some examples of popular languages which have that, as I can't
>> think of any.

> The only one I can think of is Perl, which I'm not sure counts as
> popular any more.  JavaScript allows consecutive commas in array
> literals, but they're not no-ops, they create empty array slots:

I'm fairly down on this idea for SQL, because I think it creates
ambiguity for the ROW() constructor syntax.  That is:

	(x,y) is understood to be shorthand for ROW(x,y)

	(x) is not ROW(x), it's just x

	(x,) means what?

I realize the original proposal intended to restrict the legality of
excess commas to only a couple of places, but to me that just flags
it as a kluge.  ROW(...) ought to work pretty much the same as a
SELECT list.

As already mentioned, if you can get some variant of this through the
SQL standards process, we'll probably adopt it.  But I doubt that we
want to get out front of the committee in this area.

			regards, tom lane

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