Functions and Parentheses

On Fri, Oct 6, 2017 at 2:18 PM, Igal @ Lucee.org <igal@lucee.org> wrote:

Hi,

Is current_date a function? It's a bit puzzling to me since there are no
parentheses after it, i.e.

SELECT current_date;

And not

SELECT current_date(); -- syntax error

​
It, and the others like it, behave as functions. They don't require
parentheses because the SQL standard​
​
​ defines them without parentheses.

How come `current_date` has no parenthesis but `clock_timestamp()` does?

clock_timestamp isn't standard defined and unless the standard forces us to
do otherwise function invocation requires parentheses.

See 9.9.4 (
https://www.postgresql.org/docs/9.6/static/functions-datetime.html )

David J.

"Igal @ Lucee.org" <igal@lucee.org> writes:

How come `current_date` has no parenthesis but `clock_timestamp()` does?

Because the SQL standard says that CURRENT_DATE doesn't have parentheses.
It is a function by any other measure, though.

(AFAICT, the SQL committee is unacquainted with any principles of
programming language syntax design that emerged later than the COBOL
era. Their capacity to invent new and non-orthogonal syntax for every
new feature seems boundless.)

regards, tom lane

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On 10/06/2017 02:33 PM, Tom Lane wrote:

"Igal @ Lucee.org" <igal@lucee.org> writes:

How come `current_date` has no parenthesis but `clock_timestamp()` does?

Because the SQL standard says that CURRENT_DATE doesn't have parentheses.
It is a function by any other measure, though.

(AFAICT, the SQL committee is unacquainted with any principles of
programming language syntax design that emerged later than the COBOL
era. Their capacity to invent new and non-orthogonal syntax for every
new feature seems boundless.)

This is the best statement I have read all week.

JD

regards, tom lane

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On 10/6/2017 3:10 PM, Joshua D. Drake wrote:

On 10/06/2017 02:33 PM, Tom Lane wrote:

"Igal @ Lucee.org" <igal@lucee.org> writes:

How come `current_date` has no parenthesis but `clock_timestamp()`
does?

Because the SQL standard says that CURRENT_DATE doesn't have
parentheses.
It is a function by any other measure, though.

(AFAICT, the SQL committee is unacquainted with any principles of
programming language syntax design that emerged later than the COBOL
era.  Their capacity to invent new and non-orthogonal syntax for every
new feature seems boundless.)

This is the best statement I have read all week.

+1

I also want to say that I'm using many different open source projects,
but Postgres has by far the best community support of all, not to
mention a product that is far superior to the many commercial
alternatives in the market.

It's kind of like -- I can use Postgres for free, or I can spend a lot
of money and get an inferior product with inferior support.

If Postgres had been written in Java then I'd be much more involved, but
my C/C++ skills are rather limited.

Anyway, great job guys!  And Thank you!

Igal Sapir
Lucee Core Developer
Lucee.org <http://lucee.org/&gt;