SUM rows?

[DaVuLf]

Is there a way to select a column in a table and sum all of the values? Like.. if I had a column for transactions, and I just wanted the grand total (irregardless of customer ID or any other value) how would I sum that?

Then, how would I sum it be customer ID (regardless of product ID)?

Any help would be appreciated.

Thanks,
DaVuLf

Edit:
[code]
$query = "SELECT type, SUM(price) FROM products GROUP BY type";

$result = mysql_query($query) or die(mysql_error());
[/code]