Updating Multiple Rows Based On Sums From Another Table

Hello All

I am trying to figure out if what i am attempting to do is possible and whether or not my approach is wrong to begin with.

I am trying to build a custom report for our accounting system which is Traverse from Open systems. This is what i have done in the stored procedure thus far


SET QUOTED_IDENTIFIER ON
GO
SET ANSI_NULLS ON
GO

ALTER PROCEDURE rptArFLSalesByCustItemized_sp
@custId pCustID,
@dateFrom datetime,
@dateThru datetime,
@itemIdFrom pItemId,
@itemIdThru pItemId
as
set nocount on

-- define some variables for previous year
declare @LYqty int, @LyAmt money, @LYfrom datetime, @LYthru datetime

-- set defaults
SET @itemIdFrom=ISNULL(@itemIdFrom,(SELECT MIN(itemId) FROM tblInItem))
SET @itemIdThru=ISNULL(@itemIdThru,(SELECT MAX(itemId) FROM tblInItem))
SET @LYfrom=DATEADD(YEAR,-1,@dateFrom)
SET @LYthru=DATEADD(YEAR, -1, @dateThru)

-- create small temp table to hold customer info
Create Table #tmpArCustInfo
(
custId pCustID,
custName VARCHAR (30),
)
-- populate customer temp table with info
Insert into #tmpArCustInfo
select custId, custName
from tblArCust
WHERE custId = @custId


-- create a temp table to hold the Data for each Item
Create Table #tmpArSalesItemized
(
itemId pItemId,
productLine VARCHAR (12),
pLineDesc VARCHAR (35),
descr VARCHAR (35),
LYQtySold int,
LYTDQtySold int,
QtySold int,
LYTDsales money,
totalSales money,
LastInvDate datetime,
)

-- populate the temp table with all of the inventory items
insert into #tmpArSalesItemized
select ii.itemId, ii.productLine, ip.Descr, ii.Descr, 0,0,0,0,0, NULL
from tblInItem ii, tblInProductLine ip
where ip.productLine = ii.productLine
AND ii.itemId BETWEEN @itemIdFrom AND @itemIdThru

-- update table with this years quantities
update #tmpArSalesItemized
SET QtySold = (select SUM(QtyOrdSell) from tblArHistDetail hd
where TransId IN (select TransId from tblArHistHeader where custId = @custId)
AND orderDate IN (select OrderDate from tblArHistHeader where OrderDate BETWEEN @dateFrom AND @dateThru)
AND hd.partId BETWEEN @itemIdFrom AND @itemIdThru
GROUP BY hd.partId
)

-- Return the temp tables results
select * from #tmpArSalesItemized, #tmpArCustInfo

drop table #tmpArSalesItemized, #tmpArCustInfo

return


GO
SET QUOTED_IDENTIFIER OFF
GO
SET ANSI_NULLS ON
GO


My problems begin where i want to start updating all of the Qty's of the QtySold field. I have managed to get it to write the same sum in every field but i cannot figure out how to update each row based on the sum of the qty found for that item in the tblArHistDetails table, trouble is too that there is no reference to the custId in that table either. The custId resides in tblArHistHeader and is linked to the details table via the TransId column. So really i need to update many rows based on criteria from 2 other tables.

Can anyone please help? I dont have a clue how to make this work, and most of what i have learned about sql thus far has been from opening other stored procs etc in the accounting system and just reading to see how the developers have done things.

Thanks
Jamie