CIS430 /CIS530 Lab Assignment 6

Transcription

1 CIS430 /CIS530 Lab Assignment 6 1. Drop constraints for Employee and Department tables. 2. Create triggers to implement constraint EMPDEPTFK in Table Employee based on the following rules as defined in provided DDL: FK Dno of Employee On Delete SET DEFAULT (=1) and FK Dno of Employee On Update CCADE of Dnumber PK of Department Current state of DEPARTMENT table: SELECT * FROM DEPARTMENT; Current state of EMPLOYEE table: SELECT * FROM EMPLOYEE; Add UPDATE trigger: CREATE TRIGGER EMPDEPTFK_UPDATE ON DEPARTMENT FOR UPDATE IF UPDATE(Dnumber) UPDATE EMPLOYEE SET Dno = inserted.dnumber FROM EMPLOYEE, deleted, inserted WHERE EMPLOYEE.Dno = deleted.dnumber END

2 GO Do update: UPDATE DEPARTMENT SET Dnumber = 99 WHERE Dnumber = 4; DEPARTMENT: EMPLOYEE: Employee table rows that had Dno value 4 were changed as expected, since the value was changed to 99 in Department table. Add DELETE trigger: CREATE TRIGGER EMPDEPTFK_DELETE ON DEPARTMENT FOR DELETE int = 1 UPDATE EMPLOYEE SET Dno

3 END FROM EMPLOYEE, deleted WHERE EMPLOYEE.Dno = deleted.dnumber Delete entry form DEPARTMENT table: DELETE FROM DEPARTMENT WHERE Dnumber = 5; DEPARTMENT table after deletion: EMPLOYEE table after deletion: First 5 rows of employee table have new default (=1) Dno values, because delete trigger was fired, when department dnumber = 5 was deleted from Department table. Drop both triggers: DROP TRIGGER EMPDEPTFK_DELETE; DROP TRIGGER EMPDEPTFK_UPDATE; 3. Create stored procedure SP_Audit_Dept that inserts all the history of the data changes for DEPARTMENT table. Create table for audits:

4 CREATE TABLE Audit_Dept_Table ( date_of_change DATE NOT NULL, old_dname VARCHAR(15) NOT NULL, new_dname VARCHAR(15), old_dnumber INT NOT NULL, new_dnumber INT, old_mgrssn CHAR(9) NOT NULL, new_mgrssn CHAR(9) ); Create stored procedure: CREATE PROCEDURE CHAR(9)) DATE = GETDATE() INSERT INTO Audit_Dept_Table @new_dnumber, END Create new update trigger: CREATE TRIGGER EMPDEPTFK_UPDATE ON DEPARTMENT FOR UPDATE VARCHAR(15) INT INT VARCHAR(15) INT INT IF UPDATE(Dnumber) UPDATE EMPLOYEE SET Dno = inserted.dnumber FROM EMPLOYEE, deleted, inserted WHERE EMPLOYEE.Dno = deleted.dnumber; = = = deleted.mgr_ssn FROM deleted; = = = inserted.mgr_ssn FROM inserted;

5 END Create new delete trigger: CREATE TRIGGER EMPDEPTFK_DELETE ON DEPARTMENT FOR DELETE int VARCHAR(15) INT INT = 1 UPDATE EMPLOYEE SET Dno FROM EMPLOYEE, deleted WHERE EMPLOYEE.Dno = deleted.dnumber; = = = deleted.mgr_ssn FROM deleted; END EXEC NULL; Initial DEPARTMENT table:

6 Initial EMPLOYEE table: Perform update: UPDATE DEPARTMENT SET Dname = 'Administration1' WHERE Dnumber = 99; Updated DEPARTMENT TABLE: New entry in audit table:

7 When update was performed, update trigger fired and since dnumber did not change, there was nothing to update in Employee table. New values were inserted in audit table as expected (by calling SP_Audit_Dept procedure at the end of the trigger). Perform deletion: DELETE FROM DEPARTMENT WHERE Dnumber = 99; Updated DEPARTMENT table: Updated EMPLOYEE table: New entry in audit table:

8 On deletion, EMPDEPTFK_DELETE trigger fired and tuples in Employee table have new default Dno values as expected. Also, the audit table has new entry, with NULL values for new_dname, new_dnumber and new_mgrssn.