How to implement the deletion of correspondence in the chat?

Question

PHP

Hello. I wrote a small chat for my project. With the ability to create conferences. This is what the DB looks like:

CREATE TABLE `prefix_chat_room` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `admin_id` int(11) NOT NULL ,
  `type` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `prefix_chat_message` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
  `room_id` int(11) NOT NULL,
  `user_id` int(11) NOT NULL,
  `answer_to` int(11) NOT NULL DEFAULT '0',
  `message` text NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

CREATE TABLE `prefix_chat_room_relation` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `room_id` int(11) NOT NULL,
  `user_id` int(11) NOT NULL,
  `message_id` int(11) NOT NULL DEFAULT '0'
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Now I want to implement the ability to delete a chat... If I delete the entire chat, I'll add, for example, the delete_id field to the prefix_chat_room_relation table and show only those messages whose id is greater than delete_id.
And if you do deletion by messages, how to make sure that messages are not deleted from other participants in the correspondence?

Answer 1

Make 2 flags who has already deleted and who has not on prefix_chat_message