MS-Access: sum up 2 values before building a pivot table - sql

Question

So somebody ordered cheese, beer, bread and cigarettes, and table tblItems looks like this:
iID iName iAmount iPrice iProductID iOrderID
------------------------------------------------------
1 cheese 1 2.99 11 7
2 can of beer 6 0.99 14 7
3 bread 1 2.25 15 7
4 cigarettes 1 6.99 16 7
Before feeding this order into a TRANSFORM query, I need to
summarise all items with iProductID = 11 OR iProductID = 15
name it as food
and assign to it a iProductID = 99
iProductIDs other that 14 or 99 are to be filtered out
I do not want to change the data in tblItems though.
I need it to look like this:
iID iName iAmount iPrice iProductID iOrderID
-------------------------------------------------------
1 food 1 5.24 99 7
2 can of beer 6 0.99 11 7
I've been fiddling around for more than an hour and just can't seem to grasp it.
The filtering-part is easy.
SELECT * FROM tblItems WHERE iProductID = 11 OR iProductID = 99
It is the aggregating part that gives me headaches.
Can somebody please help and point me in the right direction?

Answer 1

You want an aggregation query:
select iif(i.productid in (11, 15), 99, i.productid) as productid,
"food" as iName,
sum(i.price) as price,
i.orderid
from tblItems as i
where i.iproductid in (11, 15, 14)
group by iif(i.productid in (11, 15), 99, i.productid), i.orderid;