Update multiple variables in an IF Statement - php

Question

I am having some trouble updating multiple variables inside an IF Statement and not sure where i'm going wrong.
Here is my code:
$id = $_POST['retrive_quantity'];
$n_quantity = $_POST['n_quantity'];
$result2 = mysql_query ("SELECT * FROM stock_control WHERE id = '$id' ");
while ($row1 = mysql_fetch_array($result2))
{
$quantity=$row1['quantity'];
$threshold=$row1['threshold'];
$emailSent=$row1['email_sent'];
$orders_status=$row1['orders_status'];
$orders=$row1['orders'];
}
if ($quantity + $n_quantity > $threshold && $emailSent == 2) {
$update=0 && $orders_status=0 && $orders=0;
} else {
$update=2 && $orders_status=1 && $orders=$orders;
}
mysql_query("UPDATE stock_control SET quantity=quantity + '$n_quantity',
email_sent = '$update', orders_status = '$orders_status', orders = '$orders'
WHERE id = '$id' ");
The first line of the IF Statement works and also with just one of the variables, but fails with multiple.

Answer 1

You can not update variables like this you have to separate with ;
if ($quantity + $n_quantity > $threshold && $emailSent == 2) {
$update=0;
$orders_status=0;
$orders=0; // or $update = $orders_status = $orders=0;
} else {
$update=2;
$orders_status=1;
//$orders=$orders; //no need for this
}

Answer 2

Declare the variable before used in if block
$id = $_POST['retrive_quantity'];
$n_quantity = $_POST['n_quantity'];
$update=2;
$orders_status=1;
$orders=0;
$result2 = mysql_query ("SELECT * FROM stock_control WHERE id = '$id' ");
while ($row1 = mysql_fetch_array($result2))
{
$quantity=$row1['quantity'];
$threshold=$row1['threshold'];
$emailSent=$row1['email_sent'];
$orders_status=$row1['orders_status'];
$orders=$row1['orders'];
}
if ($quantity + $n_quantity > $threshold && $emailSent == 2) {
$update=0;
$orders_status=0;
$orders=0;
} else {
$update=2;
$orders_status=1;
$orders=$orders;
}
mysql_query("UPDATE stock_control SET quantity=quantity + '$n_quantity',
email_sent = '$update', orders_status = '$orders_status', orders = '$orders'
WHERE id = '$id' ");