How to login/logout using mysql database and php session with or without AJAX?

I need a step by step tutorial for开发者_开发知识库 using PHP mechanism to login/logout using session, with or without AJAX as a client interface.

Using mysql database as the data model.

Thanks, Damjan Dimitrioski.

---

There are many tutorials around to do similar processes, be it with plain php or with php frameworks. To avoid answering with links, I enclose instructions step by step to implement a database - session login/logout system with plain php. To allow the users to try by themselves, I list the steps instead of giving the full code. Still, I provide links to implementation examples, fully coded, at the bottom.

1. Build your users table with at least the following data:

   • id
   • username
   • password

2. To establish and check if the user is logged in, we will use one or two $_SESSION variables. A common option would be using the user id from the database. You can also have another variable registered: maybe the user name to greet them once they are logged, etc. Lets use id and username as an example.

3. Build a login page with a username/password form (html)

4. Write a method in PHP to process the login form (you can call it via ajax or at the form action). You also can write inline PHP code to do this if required.

   • start the session with session_start()
   • validate the username and password $_POST (ed) from the previous form
   • query the database for the given username and password:
     • If the user exists, save the session variables you stablished at step 2 (for our example, $_SESSION["id"])- Then redirect to the protected index.
     • If the user does not exist, print a message saying so.

5. Protect the content: write a method and use it to check if a user is logged in or not before loading your content like this:

   • start the session
   • if the session variables are set, show the content
   • if the session variables are not set, show a link to the login (or redirect the user there with header location, for example)

6. Provide a Logout page (or method to call it via ajax, for example)

   • start the session
   • unset each session variable you used at the user login
   • show the user a message or redirect to the login page/ any other action you wish to perform here

Links to tutorials and code examples implementing the solution:

• https://www.wdb24.com/session-in-php-example-for-login-logout/
• https://www.w3tweaks.com/simple-php-login-and-logout-script-using-php-session-and-database-using-mysql.html