How can I achieve three level user authentication in PHP with mysql database?

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PHP

I am working on a web portal where I have to implement three levels of users. And I need to achieve it using php and mysql what I want can be explained as follows.

level 0 user: Request some changes for website.

level 1 user: Receives the notification of level 0 user request, and he needs to approve the request.

level 2 user: Gets notified about level 1's approval and finally he/she grants the request in order to implement the changes to the website.