Just use a preceeding load for your HAVING conditions. So something like this:
SELECT Customer, count(Order) as Orders, sum(Sales) as Sales
FROM OrderTable
WHERE OrderDate >= 20100101
GROUP BY Customer
HAVING count(Order)>10
Would be written like this:
LOAD *
WHERE Orders > 10
;
LOAD Customer, count(Order) as Orders, sum(Sales) as Sales
RESIDENT OrderTable
WHERE OrderDate >= 20100101
GROUP BY Customer
