ID            NUMBER PRIMARY KEY
DEPT_CODE     VARCHAR2(5) 
...

##</code><code>##

ALTER TABLE DEPARTMENT ADD CONSTRAINT DEPT_NUM_CK_FK
FOREIGN KEY ( DEPT_CODE ) REFERENCES DEPARTMENT_CODES.CODE;

##</code><code>##

SEQ   CODE    NAME 
---   -----   -----------------------------
  1   H23R    Human Resources 
  2   1126    R & D
...