Logging Application Activities on PHP and MySQL - php

Question

I'm trying to make a small logging table on my database.
Users
+----+------+
| id | name |
+----+------+
| 1 | FOO |
| 2 | BAR |
| 3 | LOS |
+----+------+
Log_Users
+-------------+-------------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-------------------+------+-----+-------------------+-----------------------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| old_id | int(11) | YES | | NULL | |
| old_name | varchar(100) | YES | | NULL | |
| new_id | int(11) | YES | | NULL | |
| new_name | varchar(100) | YES | | NULL | |
| action_type | enum('C','U','D') | YES | | NULL | |
| time | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| doers | int(11) | YES | | NULL | |
+-------------+-------------------+------+-----+-------------------+-----------------------------+
I have a small application created using PHP to save user's id into session. How do i send this user's id value (on PHP's session) to a trigger of one of the tables to log their activities, like deleting another users or updating them? I've tried to use a trigger on log table to do all of the things, something like this.
CREATE TRIGGER userTrigger BEFORE INSERT ON Log_Users FOR EACH ROW
BEGIN
IF(new.action_type = 'C') THEN
INSERT INTO Users(id, name) VALUE(new.new_id, new.new_name);
ELSEIF(new.action_type = 'U') THEN
UPDATE Users SET id = new.new_id, name = new.new_name WHERE id = new.old_id;
ELSEIF(new.action_type = 'D') THEN
SET new.old_name = (SELECT name FROM Users WHERE id = new.old_id);
DELETE FROM Users WHERE id = new.old_id;
END IF;
END~
But, I'm struggling on the problem when users updating multiple records on the same column. At the end, what is and how to make an optimal activities logging using PHP and MySQL and how to do it? I have no solution for this problem for now. Thank you.

Answer 1

I've never done this using triggers so I can't help you with that sadly. How I usually do this:
Your users should NEVER have direct access to mysql or phpmyadmin, they should create, edit, delete and anything else using a PHP script you provide. This way you have total control over what your users can and can't do, and you narrow a lot the posible actions performed, so creating logs of them is much easier. For example:
You have a php scrip that users use to do some stuff and insert a new row, right after that you do a insert on the log table recording this last action.