Search notes:

ORA-01407: cannot update … to NULL

create table tq84_1407 (
    id    integer not null,
    val   number(7,2)
);

insert into tq84_1407 values (1, 42.9);

The following update statement throws ORA-01407: cannot update ("RENE"."TQ84_1407"."ID") to NULL:

update tq84_1407 set id = null where val > 40;

See also