Is there any way to use two combo boxes to vary one of the other type in this example (Two combo boxes where one varies the other using 2 forms cant use ajax);
Thisismydatabase(Mydatabase) 
<!DOCTYPEhtml>/*<html><head><title>Marcar</title><metacharset="utf-8"/>
</head>
<body>
<?php
if(isset($_POST['submit']))
{
include("config.php");
$Marca=$_POST['Marca'];
$Modelo=$_POST['Modelo'];
$Data=$_POST['Data'];
$tipo=$_POST['tipo'];
$Email=$_POST['Email'];
if(empty($Marca) ||empty($Modelo)||empty($Data)
)
{
echo "Deve porencher todos os valores";
}
else{
$insert_values=$mysqli->query("insert into consulta(Email,Marca,Modelo,Tipo,Data)
values('$Email','$Marca','$Modelo','$tipo','$Data')");
if($insert_values)
{
echo "<h3>Registo inserido</h3>";
}
else
{
die('Erro:(' .$mysqli->errno. ')'.$mysqli->error);
}
}
}
?>
<form method="post" enctype="multipart/form-data">
Marca: <select name="Marca" id="Marca">
<?php
include "config.php";
$results=$mysqli->query("SELECT id_Marca, Marca FROM marcas");
while($row=$results->fetch_array()){
echo "<option value='".$row['Marca']."'>".$row['Marca']."</option>";
}
?>
</select> <br> <br>
Modelo: <select name="Modelo" id="Modelo">
<?php
$results=$mysqli->query("SELECT id_Modelo,Modelo FROM modelos /*where id_Modelo like $results3*/ ");
while($row=$results->fetch_array()){
echo "<option value='".$row['Modelo']."'>".$row['Modelo']."</option>";
}
echo $results3;
?>
</select> <br> <br>
Tipo Prob: <input type="text" name="tipo" id="tipo"/>
<br>
Data Consulta: <input type="text" name="Data" value="<?php echo date('Y-m-d'); ?>" id="Data" />
<br>
Email: <input type="text" name="Email" id="Email"/>
<br>
<input type="submit" value="Guardar" name="submit"/>
</form>
</body>
</html>