class photos
{

    var $pid;
    function showactivitypics(){

        $sql = mysql_query("SELECT * FROM activity ");
        while ($row = mysql_fetch_array($sql)) {
            $picid= $row['picid'];
            $this->pid=$picid;
        }
    }

    function picname(){
        echo $this->pid;
    }
}

$photo=new photos();

<?php $photo->picname();    ?>

<?php $photo->pid; ?>