PLSQL Tutorial#21 Instead of trigger in oracle database

In this plsql tutorial we will learn Instead of trigger in oracle database
Oracle SQL Complete Tutorial/Training/Course for the beginner:
https://www.youtube.com/watch?v=3v4s3XMw4q0&list=PLiLpmqwkwkCt0QeXD8j7BwIoOaBGBRrZC
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Instead of trigger theory
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reate or replace view emp_dept_view
as select e.employee_id , e.employee_name , e.salary , d.department_name , d.department_id
from employees e , departments d
where e.department_id = d.department_id;

Views can't be updated in following of the case so that is the reason insteadof trigger has introduced
- Set operators
- Aggregate functions
- GROUP BY, CONNECT BY, or START WITH clauses
- The DISTINCT operator
- Joins (however, some join views are updatable)

create or replace view emp_dept_view_1 as
select * from employees;

select e.employee_id , e.salary ,
d.department_name , d.location
from employees e , departments d
where e.department_id = d.department_id;


CREATE [OR REPLACE] TRIGGER trigger_name
INSTEAD OF {INSERT | UPDATE | DELETE}
ON view_name
FOR EACH ROW
BEGIN

-- SQL queries

END;

CREATE OR REPLACE TRIGGER trigger_name
INSTEAD OF INSERT OR UPDATE OR DELETE
ON emp_dept_view
FOR EACH ROW enable
BEGIN
dbms_output.put_line('Hey I have truncated table'||:new.employee_id);
CASE
WHEN INSERTING THEN

Insert into DEPARTMENTS (DEPARTMENT_ID,DEPARTMENT_NAME,LOCATION)
values (:new.department_id,:new.DEPARTMENT_NAME,:new.LOCATION);

Insert into EMPLOYEES (EMPLOYEE_ID,EMPLOYEE_NAME,JOB,MANAGER_ID,
HIREDATE,SALARY,COMMISSION,DEPARTMENT_ID)
values (:new.employee_id,:new.employee_name,'dummy',0,
to_date('20-FEB-81','DD-MON-RR'),:new.salary,0,
:new.department_id);



END CASE;

END;

insert into emp_dept_view (EMPLOYEE_ID,salary, DEPARTMENT_NAME,DEPARTMENT_ID,location)
values(123, 100 , 'IT dep' , 100 , 'DELHI');

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