GROUP BY and empty queries

Hi,

sorry if this is a FAQ, but I have a bit trouble with PostgreSQL 6.5 on
a RedHat 5.2 machine:

----snip----
js=> create table testi (number int, name varchar(40));
CREATE
js=> insert into testi values (1, 'myname');
INSERT 151274 1
js=> select sum(number) from testi where name='myname';
sum
---
1
(1 row)

js=> select * from testi where name='notthere';
number|name
------+----
(0 rows)

js=> select sum(number) , name from testi where name='notthere' group by
name;
sum|name
---+----
|
(1 row)
----snip----

This crashes my little app (because of the empty row) which works fine
with Oracle:

----snip----
SQL> create table testi (n int, name varchar(40));

Table created.

SQL> insert into testi values (1, 'myname');

1 row created.

SQL> select sum(n) from testi where name='myname';

SUM(N)
----------
1

SQL> select * from testi where name='notthere';

no rows selected

SQL> select sum(n), name from testi where name='notthere' group by name;

no rows selected
----snip----

Which is the buggy one: Oracle, PostgreSQL or my Java-app?

Thanls,
Jochen