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Re: [GENERAL] Functions and Parentheses - Mailing list pgsql-general

From David G. Johnston
Subject Re: [GENERAL] Functions and Parentheses
Date
Msg-id CAKFQuwZvUJSRir_Ap_GLSgOJGWUimOnkrv2GbiAqi6=c0JCNzw@mail.gmail.com
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In response to [GENERAL] Functions and Parentheses  ("Igal @ Lucee.org" <igal@lucee.org>)
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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.

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