Re: Function that returns Boolean

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От David Fetter
Тема Re: Function that returns Boolean
Дата
Msg-id 20090223190232.GA27811@fetter.org
обсуждение исходный текст
Ответ на Function that returns Boolean  (SHARMILA JOTHIRAJAH <sharmi_jo@yahoo.com>)
Список pgsql-general
On Mon, Feb 23, 2009 at 09:39:01AM -0800, SHARMILA JOTHIRAJAH wrote:
> Hi,
> This is a simple function that returns a boolean ..

This should be an SQL function, as it doesn't do anything you need (or
would even find convenient) for a more procedural language to do:

CREATE OR REPLACE FUNCTION check_value(newValue TEXT, oldValue TEXT)
RETURNS BOOLEAN
LANGUAGE SQL
AS $$ SELECT $1 IS DISTINCT FROM $2 $$;

As others have pointed out, IS DISTINCT FROM covers the case where one
or more of the arguments is a NULL.

Cheers,
David.
>
> create or replace function check_value( newValue IN VARCHAR,
>                     oldValue IN VARCHAR ) RETURN BOOLEAN
> as
> '
> BEGIN
>     IF ( newValue != oldValue)
>         then return true;
>     else
>         return false;
>      END IF;
> END;
> '
> LANGUAGE 'plpgsql'
>
> But I get this error...what is wrong with this ?
>
> [Error] Script lines: 1-13 -------------------------
>  ERROR: syntax error at or near "RETURN"
>  Line: 2
>
> Thanks
> Sharmila
>
>
>
>
> --
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--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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