SQL>
SQL>
SQL>
SQL> create table myaudit(
2 id VARCHAR2(4 BYTE) NOT NULL,
3 old_value VARCHAR2(40 BYTE),
4 new_value VARCHAR2(40 BYTE)
5 );
Table created.
SQL>
SQL> -- create demo table
SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 First_Name VARCHAR2(10 BYTE),
4 Last_Name VARCHAR2(10 BYTE),
5 Start_Date DATE,
6 End_Date DATE,
7 Salary Number(8,2),
8 City VARCHAR2(10 BYTE),
9 Description VARCHAR2(15 BYTE)
10 )
11 /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ('01','Jason', 'Martin', to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto', 'Programmer')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('02','Alison', 'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('03','James', 'Smith', to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('04','Celia', 'Rice', to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('05','Robert', 'Black', to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('06','Linda', 'Green', to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York', 'Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('07','David', 'Larry', to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York', 'Manager')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
3 /
1 row created.
SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected.
SQL>
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER before_employee_salary_update
2 BEFORE UPDATE OF salary
3 ON employee
4 FOR EACH ROW WHEN (new.salary < old.salary * 0.75)
5 BEGIN
6 dbms_output.put_line('id = ' || :old.id);
7 dbms_output.put_line('Old salary = ' || :old.salary);
8 dbms_output.put_line('New salary = ' || :new.salary);
9 dbms_output.put_line('The salary reduction is more than 25%');
10
11 INSERT INTO Myaudit (
12 id, old_value, new_value
13 ) VALUES (
14 :old.id, :old.salary, :new.salary
15 );
16 END before_employee_salary_update;
17 /
Trigger created.
SQL>
SQL> update employee set salary = 0;
8 rows updated.
SQL>
SQL>
SQL> select * from employee;
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 0 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 0 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 0 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 0 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 0 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 0 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 0 New York Manager
08 James Cat 17-SEP-96 15-APR-02 0 Vancouver Tester
8 rows selected.
SQL>
SQL> select * from myaudit;
ID OLD_VALUE NEW_VALUE
---- ---------------------------------------- ----------------------------------------
01 1234.56 0
02 6661.78 0
03 6544.78 0
04 2344.78 0
05 2334.78 0
06 4322.78 0
07 7897.78 0
08 1232.78 0
8 rows selected.
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>
SQL> drop table myaudit;
Table dropped.
SQL>
SQL>