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'