How to use static keyword in PHP

[phpkiller]

< ?
class myClassName
{
static private $mystaticvariable; //Defining Static Variable

function __construct($value)
{
if($value != "")
{
myClassName::$mystaticvariable = $value; //Accessing Static Variable
}
$this->getStaticData();
}

public function getStaticData()
{
echo myClassName::$mystaticvariable; //Accessing Static Variable
}
}

$a = new myClassName("12");
$a = new myClassName("23");
$a = new myClassName("");
?>