Session in PHP is a very important thing, like our user login is generally used to the session of this thing, compared to the cookie to the session to be a lot safer, and our property vehicles often use the session to do temporary record save Oh.
Simple to create session
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Session_Start ();
$username = "Nostop";
Session_register ("username");
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In this example, we register a variable named username to the session with a value of nostop.
Read session
PHP built-in $_session variables can be easily accessed by setting the SESSION variable.
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Example:
Session_Start ();
echo "Registered user name:". $_session["username"]; The output registered user name is: nostop
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Destroy session
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Session_unregister () unregisters a single session variable
unset ($_session[' age '); Used to unregister SESSION variables registered with $_session[' age ')
Session_unset () Delete all registered variables
Session_destroy () Unregisters all session variables, and logs off entire sessions |
Example:
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Session_Start ();
Session_unregister ("username"); Log off a Session variable
Session_unset (); Unregistering Session Sessions
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Look at a complete session using the method,
Use session to save user login information
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Location of the database
Define (' db_host ', ' localhost ');
User name
Define (' Db_user ', ' root ');
Password
Define (' Db_password ', ' 19900101 ');
Database name
Define (' db_name ', ' test ');
?>
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Login page: login.php
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If the user is not logged in, that is, $_session[' user_id ' is not set, execute the following code
if (!isset ($_session[' user_id ')) {
if (Isset ($_post[' submit ')) {//The following code is executed when the user submits the login 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 for one-way encryption of strings
$query = "Select user_id, username from mismatch_user WHERE username = ' $user _username ' and '." Password = SHA (' $user _password ') ";
Querying with a user name and password
$data = Mysqli_query ($dbc, $query);
If the record is exactly one, set the session and redirect the page
if (Mysqli_num_rows ($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 is incorrect, set the error message
$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 is already logged in, jump directly to the already logged in page
$home _url = ' loged.php ';
Header (' Location: '. $home _url);
}
?>
<title>Mismatch-log in</title>
Msimatch-log in
if (!isset ($_session[' user_id ')) {
Echo ''. $error _msg. ' ';
?>
}
?>
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3. Login page: loged.php
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Session must be started before using variable values stored in the session
Session_Start ();
Check login status with a session variable
if (isset ($_session[' username ')) {
Echo ' You are logged as '. $_session[' username '. '
';
Click "Log Out" to go to the logout page to sign out
Echo ' Log out ('. $_session[' username ') ';
}
/** in the login page, you can take advantage of the user's SESSION such as $_session[' username '],
* $_session[' user_id '] query the database, you can do a lot of things * *
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4. Logout Session page: logout.php (redirected to lonin.php after logout)
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Even when you log off, you must start the session first to access the session variable
Session_Start ();
Check login status with a session variable
if (Isset ($_session[' user_id ')) {
To clear a session variable, set the $_session Super global variable to an empty array
$_session = Array ();
If there is a session cookie, delete it by setting the expiration time to 1 hours before
if (Isset ($_cookie[session_name ())) {
Setcookie (Session_name (), ", Time ()-3600);
}
Use the built-in Session_destroy () function to invoke the undo session
Session_destroy ();
}
Location header redirects the browser to another page
$home _url = ' login.php ';
Header (' Location: '. $home _url);
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