create table m(f1 integer not null primary key, f2 integer);
alter table m add unique(f1, f2);

create table d(f1 integer not null, f2 integer);
alter table d add foreign key(f1, f2) references m(f1, f2) on update cascade; 

insert into m(f1, f2) values (1, 1);
insert into d(f1, f2) values (1, 1);

update m set f2 = 2;
select * from d;
     F1           F2
======= ============
      1            2

SQL> update m set f2 = null;
Statement failed, SQLSTATE = 23000
violation of FOREIGN KEY constraint "INTEG_4377" on table "D"
-Foreign key references are present for the record