Session implementation in php saves user login information _ PHP Tutorial

Source: Internet
Author: User
In php, session is used to save user login information. Session is a very important thing in php. session is usually used for user login. session is much safer than cookie, at the same time, our property car session is a very important thing in php. for example, session is usually used for user login. session is much safer than cookie, at the same time, our car often uses session to save temporary records.

Simple session creation

The code is as follows:

Session_start ();
$ Username = "nostop ";
Session_register ("username ");
?>

In this example, we registered a variable named username with the value of nostop to the session.

Read session

PHP's built-in $ _ SESSION variable allows you to easily access the set session variable.

The code is as follows:

Example:
Session_start ();
Echo "the registered user name is:". $ _ SESSION ["username"]; // The output user name is nostop.
?>

Destroy session

The code is as follows:

Session_unregister () cancels a single session variable
Unset ($ _ SESSION ['age']); used to cancel a SESSION variable registered with $ _ session ['age ']
Session_unset () delete all registered variables
Session_destroy (): cancels all session variables and cancels the entire session

Example:

The code is as follows:
Session_start ();
Session_unregister ("username"); // deregister a session variable
Session_unset (); // deregister a session
?>


Let's look at a complete session usage method,

Use session to save user login information

The code is as follows:


// Database location
Define ('Db _ host', 'localhost ');
// User name
Define ('Db _ user', 'root ');
// Password
Define ('Db _ password', '123 ');
// Database name
Define ('Db _ name', 'test ');
?>

Logon page: logIn. php

The code is as follows:

// If the user is not logged on, that is, when $ _ SESSION ['User _ id'] is not set, run the following code:
If (! Isset ($ _ SESSION ['User _ id']) {
If (isset ($ _ POST ['submit ']) {// execute the following code when the user submits the logon form
$ Dbc = mysqli_connect (DB_HOST, DB_USER, DB_PASSWORD, DB_NAME );
$ User_username = mysqli_real_escape_string ($ dbc, trim ($ _ POST ['username']);
$ User_password = mysqli_real_escape_string ($ dbc, trim ($ _ POST ['password']);

If (! Empty ($ user_username )&&! Empty ($ user_password )){
// The SHA () function in MySql is used to encrypt strings in one way.
$ Query = "SELECT user_id, username FROM mismatch_user WHERE username = '$ user_username' AND". "password = SHA ('$ user_password ')";
// Query by user name and password
$ Data = mysqli_query ($ dbc, $ query );
// If one record is found, set the SESSION and redirect the page.
If (mysqli_num_rows ($ data) = 1 ){
$ Row = mysqli_fetch_array ($ data );
$ _ SESSION ['User _ id'] = $ row ['User _ id'];
$ _ SESSION ['username'] = $ row ['username'];
$ Home_url = 'loged. php ';
Header ('Location: '. $ home_url );
} Else {// if the record found is incorrect, the error message is set.
$ Error_msg = 'Sorry, you must enter a valid username and password to log in .';
}
} Else {
$ Error_msg = 'Sorry, you must enter a valid username and password to log in .';
}
}
} Else {// if the user has logged on, go directly to the logged on page
$ Home_url = 'loged. php ';
Header ('Location: '. $ home_url );
}
?>


Mismatch-Log In



Msimatch-Log In

If (! Isset ($ _ SESSION ['User _ id']) {
Echo'

'. $ Error_msg .'

';
?>


}
?>


3. logon page: loged. php

The code is as follows:


// You must enable the session before using the variable values stored in the session.
Session_start ();
// Use a session variable to check the logon status
If (isset ($ _ SESSION ['username']) {
Echo 'you are Logged as '. $ _ SESSION ['username'].'
';
// Click "Log Out" and go to the logOut page to Log Out.
Echo 'log Out ('. $ _ SESSION ['username'].') ';
}
/** On the logon page, you can use the user's session, for example, $ _ SESSION ['username'],
* $ _ SESSION ['User _ id'] queries the database, so you can do a lot of things */
?>

4. logOut session Page: logOut. php (redirection to lonIn. php after logOut)

The code is as follows:

// Even if you log out, you must start the session before accessing the session variable.
Session_start ();
// Use a session variable to check the logon status
If (isset ($ _ SESSION ['User _ id']) {
// To clear the SESSION variable, set the $ _ SESSION Super global variable to an empty array
$ _ SESSION = array ();
// If a session cookie exists, delete it by setting the expiration time to the previous one hour
If (isset ($ _ COOKIE [session_name ()]) {
Setcookie (session_name (), '', time ()-3600 );
}
// Use the built-in session_destroy () function to call and cancel a session
Session_destroy ();
}
// The location header redirects the browser to another page
$ Home_url = 'login. php ';
Header ('Location: '. $ home_url );
?>

Vivo is much safer. at the same time, our belongings and cars are often used...

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