php文件中的mysql查询错误？

Question

im trying to insert some data into my mysql database. The connection is working fine but im having a problem with sending the query correctly to the database. Below you can find the code in my php fille. I also post what for type of fields they are in the Database.

Fields in the mysql database:
Reservaties_id = int
Materialen_id = int
aantal = int
effectief_gebruikt = tinyint
opmerking = Varchar2
datum_van = date
datum_tot = date


$resID = $_REQUEST['resID'];
    $materialen_id = $_REQUEST['materialen_id'];
    $aantal = $_REQUEST['aantal'];
    $effectief_gebruikt = $_REQUEST['effectief_gebruikt'];
    $opmerking = $_REQUEST['opmerking'];
    $datum_van = date('YYYY-MM-DD',$_REQUEST['datum_van']);
    $datum_tot = date('YYYY-MM-DD',$_REQUEST['datum_tot']);



            $string = "INSERT INTO `materialen_per_reservatie`(`reservaties_id`, `materialen_id`, `aantal`, `effectief_gebruikt`, `opmerking`, `datum_van`, `datum_tot`) VALUES ($resID, $materialen_id, $aantal, $effectief_gebruikt, '$opmerking', $datum_van, $datum_tot)";
            mysql_query($string);

Answer 1

you have to include single quotes for the date fields '$dataum_van'

$string = "INSERT INTO `materialen_per_reservatie`(reservaties_id, materialen_id, aantal, effectief_gebruikt, opmerking, datum_van, datum_tot) VALUES ($resID, $materialen_id, $aantal, $effectief_gebruikt, '$opmerking', '$datum_van', '$datum_tot')";

and this is only a example query, while implementing don't forget to sanitize your inputs