concatenating a NULL value to a string will return NULL.
SELECT NULL||'Stringggg';
?column?
----------
(1 row)
There's a fonction called coalesce that replaces NULL values with a
specified value it can be usefull:
SELECT coalesce(NULL,'') || ' Stringgggg';
?column?
-------------
Stringgggg
(1 row)
SELECT coalesce('A','') || ' Stringgggg';
?column?
--------------
A Stringgggg
(1 row)
HTH
Najib.
----- Original Message -----
From: "Daniel Martini" <dmartini@uni-hohenheim.de>
To: <pgsql-general@postgresql.org>
Sent: Friday, September 24, 2004 11:33 AM
Subject: [GENERAL] plpgsql-fct. fails on NULL in record variables
> Hi all,
>
> I'm currently coding some functions in plpgsql for generating
> reports out of records in a table. Problem is: NULL values in
> records make the complete function fail.
> Here is a simple test case (original is more complex with a multi-
> table query in the for qres in select... part):
>
> create table test(
> id serial,
> descr char(4),
> data int
> );
>
> insert into test (descr, data) values ('set1', 15);
> -- record 2 does not have a data value --
> insert into test (descr) values ('set2');
>
> create function report(int) returns text as '
> declare
> qres record;
> report text;
> begin
> for qres in
> select descr, data from test where id=$1
> loop
> report:=qres.descr||'': ''||qres.data;
> end loop;
> return report;
> end;'
> language 'plpgsql';
>
> now test the function in psql:
> test=> select report(1);
> report
> ----------
> set1: 15
> (1 row)
>
> test=> select report(2);
> report
> --------
>
> (1 row)
>
> while what I want it to return in the second case is this:
> report
> --------
> set2:
> (1 row)
>
> 'set2: NULL' would be ok as well.
>
> How can I achieve this?
>
> Regards,
> Daniel
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
