I have a db table which have a row of a product amount. I want to create a loop that will calculate for me the sum for all the amounts.

```
$results = mysql_query("SELECT * 
                         FROM prod");

while($info = mysql_fetch_array($results)) {    
  $amount = $info['amount'];
}

```

`amount` is the var for each product cost. I want to get a sum for all the vars together - how can I do it?