[SQL] Functions with Null Arguments?

[Thomas Swan]

Is there anyway way to get the following to work?

table foo
id | name1   | name2
---+---------+------
 0 | Abe     | NULL
 1 | William | Bill


create function prefname(text, text)
returns text as'
declare
        name1 alias for $1;
        name2 alias for $2;
begin
        if name2 isnull
        then
                return name1;
        else
                return name2;
        end if;
end;'
language 'plpgsql';
 
if I do
select id, name1, name2, prefname(name1, name2) as pref from foo;

I wind up with

id | name1   | name2 | prefname
---+---------+-------+-----------
 0 | Abe     | NULL  | NULL
 1 | William | Bill  | Bill

instead of

id | name1   | name2 | prefname
---+---------+-------+-----------
 0 | Abe     | NULL  | Abe
 1 | William | Bill  | Bill

I assume this has to do with Postgres not executing the function is one of the arguments is missing...


-
- Thomas Swan                                   
- Graduate Student  - Computer Science
- The University of Mississippi
-
- "People can be categorized into two fundamental
- groups, those that divide people into two groups
- and those that don't."