how to pass a id variable to a query in php/mysqli?

Can someone tell me how I can pass an ID to an UPDATE query in PHP/MySQL? Every time I select "ID #3" in the drop down box of a form, my update query always reads ID #1. I believe the problem is somewhere in the code below. I've been stuck with this for 2 days. I can't tell what I'm missing in my code. Your help is greatly appreciated.

        

        

            

                
Update Existing Customer
                
Customer ID:    

                
        if(!($stmt = $mysqli->prepare("SELECT customer_id FROM customer"))){
        echo "Prepare failed: "  . $stmt->errno . " " . $stmt->error;
    }

    if(!$stmt->execute()){
        echo "Execute failed: "  . $mysqli->connect_errno . " " . $mysqli->connect_error;
    }
    if(!$stmt->bind_result($customer_id)){

        echo "Bind failed: "  . $mysqli->connect_errno . " " . $mysqli->connect_error;
    }
    while($stmt->fetch()){
        echo ' '.$customer_id.'\n';
    }
    $stmt->close();
    ?>
                
                
                
First Name:  Last Name: 

                
Email Address: 
                
Phone Number: 
                
Street Number:  Street Line 1: 
                
Street Line 2 (Apt or Unit Number): 
                
City:  State:  Zip:  
 
            
            
    

Here is the updatecustomer.php file:

    //Turn on error reporting
ini_set('display_errors', 'On');

if(!($stmt = $mysqli->prepare("UPDATE customer SET fName=?, lName=?, email=?, phone_number=?, address_no=?, address_street1=?, 
    address_street2=?, address_city=?, address_state=?, address_zip=? WHERE customer_id=?"))){
    echo "Prepare failed: "  . $stmt->errno . " " . $stmt->error;
}


echo $_POST['customer_id'];

if(!($stmt->bind_param("sssiissssii",$_POST['fName'],$_POST['lName'],$_POST['email'],$_POST['phone_number'], $_POST['address_no'],
    $_POST['address_street1'],$_POST['address_street2'],$_POST['address_city'],$_POST['address_state'], $_POST['address_zip'], $_POST['customer_id']))){
    echo "Bind failed: "  . $stmt->errno . " " . $stmt->error;
}
if(!$stmt->execute()){
    echo "Execute failed: "  . $stmt->errno . " " . $stmt->error;
} else {

    echo "Updated " . $stmt->affected_rows . " rows to customer.";

}


$stmt->close();


?>