Re: sql function with empty row

[Adrian Klaver]

On 05/16/2018 11:07 AM, Philipp Kraus wrote:
Hello,
I have defined a SQL function

CREATE OR REPLACE FUNCTION substancetrivialname(text)
     RETURNS substance
     LANGUAGE 'sql'
     COST 100
     VOLATILE
AS $BODY$
select s.* from substancetrivialname n
     join substance s on s.id = n.idsubstance
        where lower(btrim(n.name)) = lower(btrim($1));
$BODY$;

substance and substancetrivialname have got a 1-to-N relationship (for each 
substance can exist multiple trivial names).
If I call the function with a non-existing trivial name it returns a single row 
with all fields are set to NULL.

Since there can be many trivial names per substance shouldn't you be 
using SETOF?:

https://www.postgresql.org/docs/10/static/xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-SET


If I run the join query directly it returns an empty record set on a 
non-existing trivial name.
I expected equal behavior on my function, so my question is, how can I fix this?

Thanks

Phil





--
Adrian Klaver
adrian.kla...@aklaver.com