Total Value of a Mysql field I Think?

[johnp813]

I am new to PHP and Just learning as I go... Any help is GREATLY Appreciated.. This is probably simple....

I Need to get a total of one database field from multiple records.

Here is some code example..

<?php
include('variables.php');
$query = "SELECT * FROM accounts WHERE customerid = $customerid ";
$result = mysql_query($query);
$row = mysql_fetch_array($result);
$totaldue = total of $row[cost];
?>

Basic Function: Each customer may have several accounts active.. For each account there is a cost $row[cost] (perhaps different amounts depending on the type of account)

QUESTION: How do I get the total amount of $row[cost] ??

EXAMPLE:

Customerid: h12369 has 3 active accounts.. Each account has a different Value $row[cost]

Account #1 - $row [cost] = $5.00
Account #2 - $row[cost] = $10.00
Account #3 - $row[cost] = $3.00

CustomerID:h12369's TOTAL = $18.00 What is the code structure to get it to add up the cost fields and tell me the total is $18.00 .... ????

THANK YOU......

[echo]

select sum(cost) as amount from accounts where customerid = $customerid

will give a variable $row['amount'] as your previous fetching method.

[johnp813]

Thank You for your Reply Echo...

Works Great..... I had ried several things with using the sum() query, but it didnt work I must have been doing something wrong..

Thanks Again...