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<form name="invio" method="post" action="ricevi.php">
Cibi preferiti:


1<input type="checkbox" name="variabile[]" value="1">


2<input type="checkbox" name="variabile[]" value="2">


3<input type="checkbox" name="variabile[]" value="3">


4<input type="checkbox" name="variabile[]" value="4">






foreach ($_REQUEST['variabile'] as $key=> $val)
{
$query2 = "SELECT * FROM tabella WHERE id IN (".implode(",", $_POST['variabile']).")";
}

echo $query;