create table test (id char(5) not null, datum date not null);
commit;
alter table test add constraint pk_test primary key (id,datum);
commit;
insert into test (id, datum) values ('08001',cast('01.01.2008' as date));
insert into test (id, datum) values ('08001',cast('01.02.2008' as date));
insert into test (id, datum) values ('08001',cast('01.03.2008' as date));
insert into test (id, datum) values ('08002',cast('01.02.2008' as date));
insert into test (id, datum) values ('08002',cast('01.03.2008' as date));
insert into test (id, datum) values ('08003',cast('01.03.2008' as date));
commit;
select distinct datum from test order by datum;
raised exception: "field id not found".