mydb=> ALTER TABLE CUSTOMERS
mydb->      ADD CONSTRAINT HASREP
mydb->            FOREIGN KEY ( CUST_NUM ) REFERENCES SALESREPS ( EMPL_NUM ) ON DELETE SET NULL;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ERROR:  hasrep referential integrity violation - key referenced from customers not found in salesreps
mydb=>

mydb=> ALTER TABLE OFFICES
mydb->     ADD CONSTRAINT HASMGR
mydb->          FOREIGN KEY  ( MGR ) REFERENCES SALESREPS ( EMPL_NUM ) ON DELETE SET NULL;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ALTER
mydb=>

mydb=> ALTER TABLE SALESREPS
mydb->      ADD CONSTRAINT SELF
mydb->           FOREIGN KEY (MANAGER ) REFERENCES SALESREPS ( EMPL_NUM ) ON DELETE SET NULL;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ERROR:  self referential integrity violation - key referenced from salesreps not found in salesreps
mydb=>

mydb=> ALTER TABLE SALESREPS
mydb->      ADD CONSTRAINT WORKSIN
mydb->            FOREIGN KEY ( REP_OFFICE ) REFERENCES OFFICES ( OFFICE ) ON DELETE SET NULL;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ERROR:  worksin referential integrity violation - key referenced from salesreps not found in offices
mydb=>

mydb=> ALTER TABLE ORDERS
mydb->      ADD CONSTRAINT PLACEBY
mydb->           FOREIGN KEY ( CUST )  REFERENCES CUSTOMERS ( CUST_NUM ) ON DELETE CASCADE;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ALTER
mydb=>

mydb=> ALTER TABLE ORDERS
mydb->      ADD CONSTRAINT TAKENBY
mydb->           FOREIGN KEY  ( REP )  REFERENCES SALESREPS ( EMPL_NUM ) ON DELETE SET NULL;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ALTER
mydb=>

mydb=> ALTER TABLE ORDERS
mydb->      ADD CONSTRAINT ISFOR
mydb->           FOREIGN KEY ( MFR , PRODUCT ) REFERENCES PRODUCTS ( MFR_ID , PRODUCT_ID ) ON DELETE RESTRICT;
NOTICE:  ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ALTER
mydb=>