트리거

select employees;
--백업 테이블 복사
create table empbak as select  * from employee

--트리거 연습
create or replace trigger dele_emp
	before delete on employees
begin
	insert into empbak
    	select * from employees where employee_id = 174;
end;
/

delete from employees where emplyee_id = 174;

select * from employees where employee_id = 174;
select * from empbak where employee_id = 174;

-- 함수연습
create or REPLACE FUNCTION dname(dept in int)
	return varchar
    IS
    	dnm VARCHAR(30)
   	begin
    	select departmet_name into dnm
        	from departments
            where departmet_id = dept_id;
            
            return dnm;
    end;
        
	select last_name, dname(department_id) dnm
    from employees