Examples of Oracle triggers

         This article demonstrates oracle Use of triggers , For a rainy day

--  Create a table , In the future, we need to create triggers on this table 
create table baby_test
(id number(20),
name varchar(50),
birthday date,
login_date timestamp
);

--  Create a table that holds trigger operations 
-- drop table baby_test_log;
create table baby_test_log
(id number(20),
name varchar(50),
insert_date date default sysdate,
operate varchar2(50)
);


--  Create a trigger . When the baby_test Table data insertion , When you modify and delete , towards baby_test_log Insert data 
CREATE OR REPLACE TRIGGER trg_baby_test BEFORE
    INSERT OR UPDATE or delete ON baby_test
FOR EACH ROW DECLARE
    -- local variables here
 BEGIN
    CASE
        WHEN inserting THEN
            INSERT INTO baby_test_log (
                id,
                name,
                operate
            ) VALUES (
                :new.id,
                :new.name,
                'inserting'
            );

        WHEN updating('name') THEN
            INSERT INTO baby_test_log (
                id,
                name,
                operate
            ) VALUES (
                :old.id,
                :old.name,
                'updating name'
            );
            
        WHEN deleting THEN
            INSERT INTO baby_test_log (
                id,
                name,
                operate
            ) VALUES (
                :old.id,
                :old.name,
                'deleting'
            );

    END CASE;
  END;

--  Test triggers 
insert into baby_test
select 1,'baby',to_date('19990101','yyyymmdd'), sysdate from dual;

select * from baby_test;

update baby_test
set name = 'hugh'
where id = 1;

delete from baby_test where id = 1;

--  View the results of the trigger 
select * from baby_test_log;