[Que]How to express the variable in this example?

Question

I want to know how to express this variable in this example in the red part
/* Variables */
$old=$row_rs_archive['old'];
$new=$row_rs_archive['new'];
$total=$old+$new;
echo $total;
if (array_key_exists('doit', $_POST)) {
     $done = mysql_query('UPDATE temp SET cur_total = $total') or die(mysql_error());
echo works fine and show the total value , but in the UPDATE command , it doesn't work ,
I get this error
1500 Unknown column '$total' in 'field list'
notice 1500 comes from echo $total
Thanks...

Answer 1

I only took a quick glance, but I suspect it is because you're using single quotes for the query string. PHP will not parse variables in single quotes and will treat it as a literal string.
Try this:
$done = mysql_query("UPDATE temp SET cur_total = $total") or die(mysql_error());
If that doesn't quite get you there, try concatenation instead.