$result = mysql_query("select * from calendar");
while ($r = mysql_fetch_array($result)){
	$i = 0;
	$list[$r['year']][$r['month']][$r['day']][]=$r['teacher'];
	$list[$r['year']][$r['month']][$r['day']][]=$r['subject'];	
	$list[$r['year']][$r['month']][$r['day']][]=$r['block'];
	$list[$r['year']][$r['month']][$r['day']][]=$r['description'];
	$i++;
}

Array
(
    [2005] => Array
        (
            [1] => Array
                (
                    [15] => Array
                        (
                            [0] => teacher
                            [1] => subject
                            [2] => a
                            [3] => description
                            [4] => teacher
                            [5] => subject
                            [6] => a
                            [7] => description
                        )

                    [12] => Array
                        (
                            [0] => teacherasdf
                            [1] => subjectet3
                            [2] => a
                            [3] => descriptionsadf
                        )

                    [8] => Array
                        (
                            [0] => teacherasdfe
                            [1] => subjectasdf
                            [2] => a
                            [3] => description2354wed
                        )

                )

        )

)