Detailed introduction to PHP session storage method_PHP tutorial

PHP provides three ways to store sessions: File/Memory/Custom storage, the default is to use file storage.It is not convenient to use this method on websites with high traffic. This is very suitable, because this will lead to a large amount of input and output redundancy.
The following introduces a session storage method based on the Mysql database.
The first configuration to be performed is as follows:
1>In php.ini, change the files in session.save_handler = files to User, and other defaults are sufficient. Restart Apache (it seems to be OK without changing it)
2>This example creates The database name is php, username: root password:root
The table structure of the database designed in this example is as follows:

Copy code The code is as follows:

create table mysession(
session_key char(32) not null, 
session_data text,
session_expiry int(11),
primary key(session_key)
);

The first column stores the session ID, the second column stores the data in the session, and the third column stores the validity period, haha ​​(the table structure is that simple)
The following is The key custom function implementation session_set_save_handler(...)

Copy code The code is as follows:

function mysession_open($save_path, $session_name)
{
@mysql_connect("localhost", "root", "root") //Needed before selecting the database Connect to the database server first
or die("Database server connection failed");
@mysql_select_db("php") //Select database mydb
or die("Database does not exist or is unavailable");
return true;
}
function mysession_close()
{
return true;
}
function mysession_read($key)
{
@mysql_connect(" localhost", "root", "root") //You need to connect to the database server before selecting the database
or die("Database server connection failed");
@mysql_select_db("php") //Select the database mydb
or die("The database does not exist or is unavailable");
$expiry_time = time(); //Get the Session expiration time
//Execute the SQL statement to get the value of the Session
$query = @mysql_query("select session_data from mysession "
."where session_key = '$key' and session_expiry > $expiry_time")
or die("SQL statement execution failed");
if($row = mysql_fetch_array($query))
return $row['session_data'];
else
return false;
}
function mysession_write($key, $data)
{
@mysql_connect("localhost", "root", "root") //You need to connect to the database server before selecting the database
or die("Database server connection failed");
@mysql_select_db("php" ) //Select the database mydb
or die("Database does not exist or is unavailable");
$expiry_time = time() + 1200; //Get the Session expiration time
//Query the key value of the Session Does it already exist? /If it does not exist, perform the insert operation, otherwise perform the update operation
if(mysql_numrows($query) == 0)
{
//Execute the SQL statement to insert the value of the Session
$query = @mysql_query("insert into mysession values('$key', '$data', $expiry_time)")
or die("SQL statement execution failed");
}
else
{
//Execute SQL statements to update the value of Session
$query = @mysql_query("update mysession set "
."session_data = '$data', session_expiry = $expiry_time "
."where session_key = '$key'")
or die("SQL statement execution failed");
}
return $query;
}
function mysession_destroy($key)
{
@mysql_connect("localhost", "root", "root") //You need to connect to the database server before selecting the database
or die("Database server connection failed");
@mysql_select_db("php" ) //Select database mydb
or die("Database does not exist or is unavailable");
//Execute SQL statement to delete Session
$query = @mysql_query("delete from mysession where session_key = '$ key'")
or die("SQL statement execution failed");
return $query;
}
function mysession_gc($expiry_time)
{
@mysql_connect("localhost ", "root", "root") //You need to connect to the database server before selecting the database
or die("Database server connection failed");
@mysql_select_db("php") //Select database mydb
or die("Database does not exist or is unavailable");
$expiry_time = time();
//Execute SQL statement to delete Session
$query = @mysql_query("delete from mysession where session_expiry < $expiry_time")
or die("SQL statement execution failed");
return $query;
}
//Set user-defined Session storage
session_set_save_handler('mysession_open' ,
'mysession_close',
'mysession_read',
'mysession_write',
'mysession_destroy',
'mysession_gc');
?>


The last part is the test code

1>Save page save.php

Copy code

The code is as follows:include('user-define-session-inc.php'); //File containing session_set_save_handler definition

session_start();

$_SESSION['username' ] = "Simon";
$_SESSION['password'] = "123456";
?>



2. Display page show.php

Copy code

The code is as follows:include('user-define-session-inc.php '); //File containing session_set_save_handler definition

session_start();

echo "UserName:".$_SESSION['username']."
";
echo "PassWord:". $_SESSION['password']."
";
?>


Additional little experience: One day when I was trying to store the session again, I found this error on the page
Failed to initialize storage module
After looking for relevant information, I found out that my session storage uses database file storage. , and when session_start(), my database has not woken up yet...

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