DROP TABLE dept CASCADE CONSTRAINTS;
CREATE TABLE DEPT
       (DEPTNO NUMBER(2),
        DNAME  VARCHAR2(14),
        LOC    VARCHAR2(13) );
ALTER TABLE dept
  ADD (CONSTRAINT pk_dept
       PRIMARY KEY (deptno));

DROP TABLE emp CASCADE CONSTRAINTS;
CREATE TABLE EMP
       (EMPNO    NUMBER(4) NOT NULL,
        ENAME    VARCHAR2(10),
        JOB      VARCHAR2(9),
        MGR      NUMBER(4),
        HIREDATE DATE,
        SAL      NUMBER(7,2),
        COMM     NUMBER(7,2),
        DEPTNO   NUMBER(2));
ALTER TABLE emp
  ADD (CONSTRAINT fk_emp
         FOREIGN KEY (deptno) REFERENCES dept);