forgotpassword.php - ?php if isset $ POST update {...

<?php
if(isset($_POST['update']))
{
$email=$_POST['email'];
$mobile=$_POST['mobile'];
$newpassword=md5($_POST['newpassword']);
$sql ="SELECT EmailId FROM tblusers WHERE EmailId=:email and ContactNo=:mobile";
$query= $dbh -> prepare($sql);
$query-> bindParam(':email', $email, PDO::PARAM_STR);
$query-> bindParam(':mobile', $mobile, PDO::PARAM_STR);
$query-> execute();
$results = $query -> fetchAll(PDO::FETCH_OBJ);
if($query -> rowCount() > 0)
{
$con="update tblusers set Password=:newpassword where EmailId=:email and
ContactNo=:mobile";
$chngpwd1 = $dbh->prepare($con);
$chngpwd1-> bindParam(':email', $email, PDO::PARAM_STR);
$chngpwd1-> bindParam(':mobile', $mobile, PDO::PARAM_STR);
$chngpwd1-> bindParam(':newpassword', $newpassword, PDO::PARAM_STR);
$chngpwd1->execute();
echo "<script>alert('Your Password succesfully changed');</script>";
}
else {
echo "<script>alert('Email id or Mobile no is invalid');</script>";
}
}
?>
<script type="text/javascript">
function valid()
{
if(document.chngpwd.newpassword.value!= document.chngpwd.confirmpassword.value)
{
alert("New Password and Confirm Password Field do not match !!");
document.chngpwd.confirmpassword.focus();
return false;
}
return true;
}
</script>
<div id="forgotpassword" class="modal fade">
<div class="modal-dialog modal-xl">
<div class="modal-content">