PHP Singleton Mode

The Singleton mode, as its name implies, has only one instance. Therefore, in database operations, it is important to allow only one instance to exist in the same database. <? PHP

Class   MySQL
{
Protected   $ DB ;
Static   Private   $ Instance   =   Null ;
/* *
* Obtain the database connection.
*
*/
Private   Function Getdb ()
{

// Existing connection
If ( Isset (Self :: $ Instance ))
{
$ This -> DB = Self :: $ Instance ;
}
Else
{
// None
Global   $ __Db __ ;
Extract ( $ __Db __ );
$ DSN   =   " MySQL: host = $ Host ; Port = $ Port ; Dbname = $ Database " ;

Try {
$ This -> DB =   New PDO ( $ DSN ,   $ User ,   $ Password );
} Catch (Pdoexception $ E ){
Echo   ' Connection Failed: '   .   $ E -> Getmessage ();
}
Self :: $ Instance   =   $ This -> DB;
}
}
/* *
* Run SQL
*
* @ Param SQL $ SQL
*/

Private FunctionQuery ($ SQL)
{
$ This->Getdb ();
......
}

}
?>