lab4

CREATE OR REPLACE TRIGGER SALARY_DIFF_TRIG

BEFORE INSERT OR UPDATE OR DELETE ON CUSTOMER

FOR EACH ROW

DECLARE

old_salary number;

new_salary number;

BEGIN

IF INSERTING THEN

DBMS.OUTPUT.PUT_LINE('NEW SALARY:'||:NEW.salary);

ELSIF UPDATING THEN

old_salary:=:OLD.salary;

new_salary:=:NEW.salary;

IF old_salary IS NULL THEN

old_salary:=0;

END IF;

IF new_salary IS NULL THEN

new_salary:=0;

END IF;

DBMS.OUTPUT.PUT_LINE('Old Salary'||old_salary);

DBMS.OUTPUT.PUT_LINE('New Salary'||new_salary);

DBMS.OUTPUT.PUT_LINE('SALARY DIFF'||(new_salary-old_salary));

ELSIF DELETING THEN

DBMS.OUTPUT.PUT_LINE('Old Salary'||:OLD.salary);

END IF;

END;

/

first do set serveroutput ON

then create table()

then edit filename

then a prompt will open write all program except insert and update operation

then after saving close the program

then write @filename then do insert and update operation