konvertera datepicker-datum till mysql-datum

Du bör använda DateTime::createFromFormat

Ex:

$date = DateTime::createFromFormat('m/d/Y','02/10/2015');
echo $date->format("Y-m-d");
// 2015-02-10

Så i ditt fall

$from = $_GET['from'];
$date = DateTime::createFromFormat('m/d/Y',$from);
$from_date = $date->format("Y-m-d");