Re: Trailing comma support in SELECT statements

Andrew Dunstan wrote
> On 10/03/2014 12:20 PM, Bruce Momjian wrote:
>> On Sun, Sep 28, 2014 at 01:42:46PM +0200, Bogdan Pilch wrote:
>>> Hi,
>>> I have created a small patch to postgres source (in particular the
>>> psql part of it) that accepts trailing comma at the end of list in
>>> SELECT statement.
>>>
>>> The idea is to be able to say both (with the same result):
>>> SELECT a, b, c from t;
>>> SELECT a, b, c, from t;
>>>
>>> Attached you can find a patch containing regression test (incorporated
>>> into the serial_schedule).
>>> My patch is relative to origin/REL9_4_STABLE branch as that is the one
>>> I started from.
>>>
>>> My plea is to have this change merged into the main stream so that it
>>> becomes available in upcoming releases.
>>>
>>> This modification does not require any interaction with user.
>>> It does not create any backward compatibility issues.
>> Interesting --- I know some languages allow trailing delimiters, like
>> Perl and Javascript. Could this mask query errors? Does any other
>> database accept this? Seems this would need to be done in many other
>> places, like UPDATE, but let's first decide if we want this.
>>
>> FYI, it is usually better to discuss a feature before showing a patch.
>>
>
> Javascript might accept it, but it's not valid JSON.
>
> The case for doing it is that then you can easily comment out any entry
> at all in a select list:
>
> select
> foo as f1,
> bar as f2,
> -- baz as f3,
> from blurfl

Should we also allow:

SELECT
, col1
, col2
, col3
FROM ...

?

The other reason for this would be to build dynamic SQL more easily via a
loop.

Barring arguments showing danger allowing I don't see a reason to reject
this; let people decide whether they want to utilize it on stylistic or
compatibility grounds.

David J.

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