Introduction to database triggers - triggers that modify data, triggers that delete data

1. Triggers that modify data

Triggers that modify data

create trigger tb_user_update_trigger
	after update on tb_user for each row
begin
	insert int user_logs(id,operation,operate_time,operate_id,operate_params)VALUES
	(null,'update',now(),new.id,concat
	('更新之前的数据：id=',new.id,',name=',new.name,', phone=',new.phone,', email=',new.email,', profession=',new.profession
	' | 更新之后的数据：id=',new.id,',name=',new.name,', phone=',new.phone,', email=',new.email,', profession=',new.profession));
end;

show triggers;

update data

update tb_user set age = 32 where id = 23;

How many times does the following trigger fire? Several pieces of data are triggered several times.

update tb_user set age = 32 where id <= 5;

2. Trigger to delete data

create trigger tb_user_delete_trigger
	after delete on tb_user for each row
begin
	insert int user_logs(id,operation,operate_time,operate_id,operate_params)VALUES
	(null,'delete',now(),old.id,concat
	('删除之前的数据：id=',new.id,',name=',new.name,', phone=',new.phone,', email=',new.email,', profession=',new.profession);
end;

show triggers;

delete from tb_user where id = 5;