I have a mysql table with items in relation to their order.

CREATE DATABASE IF NOT EXISTS `sqltest`;
USE `sqltest`;

DROP TABLE IF EXISTS `testdata`;
CREATE TABLE `testdata` (
  `orderID` varchar(10) DEFAULT NULL,
  `itemID` varchar(10) DEFAULT NULL,
  `qtyOrdered` int(10) DEFAULT NULL,
  `sellingPrice` decimal(10,2) DEFAULT NULL
)

INSERT INTO `testdata`(`orderID`,`itemID`,`qtyOrdered`,`sellingPrice`) 
values ('1','a',1,'7.00'),('1','b',2,'8.00'),('1','c',3,'3.00'),('2','a',1,'7.00'),('2','c',4,'3.00');

Intended Result:

A = (1+1)2

B = 2

C = (2+4)6 <- most popular

How do I add up all the qty's for each item and result the highest one?

It should be fairly strait forward but I'm new to SQL and I can't work this one out :S

Solution needs to be mysql and or php.

I guess there needs to be some sort of temporary tally variable for each item ID, but that seems like it could get messy with too many items.