I'm having trouble understanding FK's and NULL's. It appears I can insert a null value to a foreign key which is not what I would expect. Is the "solution" to put NOT NULL on the column definition? Thanks, -joe RH5 10.2.0.4 (Hope this formats OK) SQL> create table test2 2 (t2_pk number, 3 lastname varchar2(50), 4 constraint pk_t2 primary key (t2_pk) validate) 5 / Table created. SQL> create table test1 2 (t1_pk number, 3 name varchar2(50), 4 test2_fk number, 5 constraint fk_test2 foreign key (test2_fk) 6 references test2 (t2_pk) validate, 7 constraint pk_t1 primary key (t1_pk) validate) 8 / Table created. SQL> insert into test2 values (1, 'Smith'); 1 row created. SQL> insert into test1 values (1, 'Joe', 1); 1 row created. SQL> insert into test1 values (2, 'Bill', 2); insert into test1 values (2, 'Bill', 2) * ERROR at line 1: ORA-02291: integrity constraint (INSPPROD.FK_TEST2) violated - parent key not found SQL> insert into test1 values (2, 'Bill', NULL); 1 row created. SQL> commit; Commit complete. -- //www.freelists.org/webpage/oracle-l