Re: Why is this function wrong

On Oct 24, 2005, at 11:27 AM, Johan Wehtje wrote:

> This is probably obvious but I am not seeing what is going wrong
> with this function definition:
>
> CREATE OR REPLACE FUNCTION "public"."cproc_hli" (bgtemp NUMERIC,
> humidity NUMERIC, wspeed NUMERIC) RETURNS NUMERIC AS
> IF ($1 < 25)
> THEN
> SELECT (10.66 * (0.28 * $2)+(1.3 * $1) - $3)
> ELSE
> SELECT (8.62 * (0.38 * $2) + (1.55 * $1) - (0.5 * $3) + (exp(- $3 +
> 2.4)))
> END IF
> LANGUAGE 'plpgsql' VOLATILE RETURNS NULL ON NULL INPUT SECURITY
> INVOKER;
>
> ERROR:  syntax error at or near "IF" at character 119
> LINE 2: IF ($1 < 25)
>
> I have tried with dollar quoting around the function body, changing
> the maguage to sql and using CASE ... WHEN instead of IF , tried
> Brackets and no brackets around the Boolean expression.. and a
> number of other variations, as well as rereading the Documentation.
>
> I have also tried not having aliases/names for the arguments.
>
> In every case I always get the syntax error directly after "AS".
>
> Can somebody point what is probably obvious.
>
> Cheers
> Johan Wehtje

This version will compile, but it won't do anything useful:

CREATE OR REPLACE FUNCTION "public"."cproc_hli" (bgtemp NUMERIC,
humidity NUMERIC, wspeed NUMERIC) RETURNS NUMERIC AS $$
BEGIN
IF (bgtemp < 25) THEN
PERFORM (10.66 * (0.28 * humidity)+(1.3 * bgtemp) - wspeed);
ELSE
PERFORM (8.62 * (0.38 * humidity) + (1.55 * bgtemp) - (0.5 * wspeed)
+ (exp(- wspeed + 2.4)));
END IF;
END;
$$ LANGUAGE 'plpgsql' VOLATILE RETURNS NULL ON NULL INPUT SECURITY
INVOKER;

You were missing some basic syntactic requirements, including a BEGIN/
END block, as well as several semicolons. You will also need to
SELECT into a variable if you want anything useful to happen with the
results. I've replaced your SELECTs with PERFORMs to recreate your
function as originally written.

I recommend a closer reading of the chapter on PL/pgSQL:

http://www.postgresql.org/docs/8.0/static/plpgsql.html

--
Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC

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