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.