PL/pgSQL a great procedural language for PostgreSQL

Hi all,

----I'm trying to understand this very interesting language PL/pgSQL
thanks to Jan Wieck,
----finally we can trap NULL values as in:

create function len(text) returns text as '
declare
nonullo alias for $1;
begin
if nonullo then
return length(nonullo);
else
return ''<NULL>'';
end if;
end;' language 'plpgsql';
CREATE

select len(c) from a;
len
------
12
<NULL>
<NULL>
<NULL>
12
(5 rows)

------I'm trying to create a function that returns a value instead of
NULL.
------The following one works well:

create function nvl(integer) returns integer as '
declare
nullo integer := 0;
nonullo alias for $1;
begin
if NONULLO then
return NONULLO;
else
return NULLO;
end if;
end;' language 'plpgsql';
CREATE

select nvl(i) from a;
nvl
-------
0
0
2232767
0
(4 rows)

------I would like to report this little thing, seems PL/pgSQL isn't
case insensitive:
drop function nvl(integer,integer);
DROP
create function nvl(integer) returns integer as '
declare
NULLO integer := 0;
NONULLO alias for $1;
begin
if NONULLO then
return NONULLO;
else
return NULLO;
end if;
end;' language 'plpgsql';
CREATE

select nvl(i) from a;
ERROR: attribute 'nonullo' not found

-------and seems it returns only constant values:

drop function nvl(integer,integer);
DROP
create function nvl(integer,integer) returns integer as '
declare
nonullo alias for $1;
nullo ALIAS FOR $2;
begin
if NONULLO then
return NONULLO;
else
return NULLO;
end if;
end;' language 'plpgsql';
CREATE

select nvl(i,0) from a;
nvl
-------

2232767

(4 rows)

Jose'