DEPTNO (Primary Key of referenced table) DNAME LOC
20 RESEARCH DALLAS
30 SALES NEW YORK
40  MARKETING BOSTON
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO (Foreign Key; values in dependent table must match a value in unique key or primary key of referenced table)
7329 SMITH CEO N/A 17-DEC-85 9,000.00 N/A 20
7499 ALLEN VP-SALES 7329 20-FEB-90 7,500.00 100.00 30
7521 WARD MANAGER 7499 22-FEB-90 5,000.00 200.00 30
7586 JONES SALESMAN 7521 02-APR-90 2,975.00 400.00 20
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO Comments
7571 FORD MANAGER 7499 23-FEB-90 5,000.00 200.00 50 This row violates the referential constraint because "50" is not present in the referenced table's primary key; therefore, the row is now allowed in the table.
7571 FORD MANAGER 7499 23-FEB-90 5,000.00 200.00 N/A This row is allowed in the table because a null value is entered in the DEPTNO column; however, if a not null constraint is also defined for this column, this row is not allowed.