$sql= "select * from t_datestudy where id='4750' and agreemode='2' and school_agree !='1'";       

    $result = mysql_query($sql,$connection);

    $app = mysql_fetch_array($result);

    mysql_free_result($result);

    $dt1 = $app['CDATE'] . ' ' . $app['START_TIME'] ;

    $dt2 = date('Y-m-d H:i:s',strtotime('+2 Hour'));

    if ($dt2 > $dt1)

        echo "exceed";

    else

        echo "ok";