Use triggers to implement backup of deleted data

--postgresql触发器测试
create table person(
p_no int PRIMARY KEY,
p_name VARCHAR(40),
age int
);
--备份表
create table person_back(
p_no int PRIMARY KEY,
p_name VARCHAR(40),
age int
);

--创建触发器执行函数
create or replace FUNCTION person_back_trigger()
RETURNS TRIGGER as $$
BEGIN	
	INSERT INTO person_back VALUES(OLD.p_no,OLD.p_name,OLD.age);
	RETURN OLD;
end;
$$
LANGUAGE plpgsql;

DELETE FUNCTION person_delete_trigger;
--创建触发器
CREATE TRIGGER delete_person_trigger
	BEFORE DELETE on person
FOR EACH ROW EXECUTE procedure person_back_trigger();

INSERT INTO person VALUES(1,'111','11');

INSERT INTO person VALUES(2,'222','22');

select * from person_back;
delete from person where p_no=1;
select * from person_back;
delete from person where p_no=2;
select * from person_back;