Trouble creating SQL Query to update line item amounts - sql-server

Question

I'm going to preface this question with the disclaimer that creating what I call "complex" queries isn't in my forte. Most of the time, there is a much simpler way to accomplish what I'm trying to accomplish so if the below query isn't up to par, I apologize.
With that said, I have a table that keeps track of Vendor Invoices and Vendor Invoice Items (along with a Vendor Invoice Type and Vendor Invoice Item Type). Our bookkeeper wants a report that simply shows: Vendor | Location | Inv Number | Inv Type | Item Type | Inv Date | Rental Fee | Restock Fee | Shipping Fee | Line Item Cost | Total (Line Item + Fees)
Most of the time, one vendor invoice is one line. However, there are exceptions where a vendor invoice can have many item types, thus creating two rows. Not a big deal EXCEPT the fees (Rental, Restock, Shipping) are attached to the Vendor Invoice table. So, I first created a query that checks the temp table for Invoices that have multiple rows, takes the last row, and zero's out the fees. So that only one line item would have the fee. However, our bookkeeper doesn't like that. Instead, she'd like the fees to be "distributed" among the line items.
So, if a vendor invoice has a $25 shipping charge, has two line items, then each line item would be $12.50.
After working with the query, I got it to update the Last Row to be the adjusted amount but row 1+ would have the original amount.
I'm going to post my entire query here (again - I'm sorry that this may not be the best looking query; however, suggestions are always welcome)
DROP TABLE #tVendorInvoiceReport
DROP TABLE #tSummary
SELECT v.Name AS Vendor ,
vii.Location ,
vi.VendorInvNumber ,
vit.Descr AS InvoiceType ,
vii.VendorInvoiceItemType ,
CONVERT(VARCHAR(10), vi.VendorInvDate, 120) VendorInvDate ,
vi.RentalFee ,
vi.RestockFee ,
vi.ShippingFee ,
SUM(vii.TotalUnitCost) TotalItemCost ,
CONVERT(MONEY, 0) TotalInvoice ,
RowID = IDENTITY( INT,1,1)
INTO #tVendorInvoiceReport
FROM dbo.vVendorInvoiceItems AS vii
JOIN dbo.VendorInvoices AS vi ON vii.VendorInvID = vi.VendorInvID
JOIN dbo.Vendors AS v ON vi.VendorID = v.VendorID
JOIN dbo.VendorInvoiceTypes AS vit ON vi.VendorInvTypeID = vit.VendorInvTypeID
WHERE vi.VendorInvDate >= '2012-01-01'
AND vi.VendorInvDate <= '2012-01-31'
GROUP BY v.Name ,
vii.Location ,
vi.VendorInvNumber ,
vit.Descr ,
vii.VendorInvoiceItemType ,
CONVERT(VARCHAR(10), vi.VendorInvDate, 120) ,
vi.RentalFee ,
vi.RestockFee ,
vi.ShippingFee
ORDER BY v.Name ,
vii.Location ,
vi.VendorInvNumber ,
vit.Descr ,
vii.VendorInvoiceItemType ,
CONVERT(VARCHAR(10), vi.VendorInvDate, 120)
SELECT VendorInvNumber ,
COUNT(RowID) TotalLines ,
MAX(RowID) LastLine
INTO #tSummary
FROM #tVendorInvoiceReport
GROUP BY VendorInvNumber
WHILE ( SELECT COUNT(LastLine)
FROM #tSummary AS ts
WHERE TotalLines > 1
) > 0
BEGIN
DECLARE #LastLine INT
DECLARE #NumItems INT
SET #LastLine = ( SELECT MAX(LastLine)
FROM #tSummary AS ts
WHERE TotalLines > 1
)
SET #NumItems = ( SELECT COUNT(VendorInvNumber)
FROM #tVendorInvoiceReport
WHERE VendorInvNumber IN (
SELECT VendorInvNumber
FROM #tSummary
WHERE LastLine = #LastLine )
)
UPDATE #tVendorInvoiceReport
SET RentalFee = ( RentalFee / #NumItems ) ,
RestockFee = ( RestockFee / #NumItems ) ,
ShippingFee = ( ShippingFee / #NumItems )
WHERE RowID = #LastLine
DELETE FROM #tSummary
WHERE LastLine = #LastLine
--PRINT #NumItems
END
UPDATE #tVendorInvoiceReport
SET TotalInvoice = ( TotalItemCost + RentalFee + RestockFee + ShippingFee )
SELECT Vendor ,
Location ,
VendorInvNumber ,
InvoiceType ,
VendorInvoiceItemType ,
VendorInvDate ,
RentalFee ,
RestockFee ,
ShippingFee ,
TotalItemCost ,
TotalInvoice
FROM #tVendorInvoiceReport AS tvir
I sincerely appreciate anyone who took the time to read this and attempt to point me in the right direction.
Thank you,
Andrew
PS - I did try and remove "WHERE RowID = #LastLine" from the first Update, but that changed the Shipping Fees for the first line with two items to "0.0868" instead of 12.50 ($25/2)

Answer 1

If I understand correctly, you're looking for a way to split something like an invoice shipping fee over one or more invoice items.
I created some sample invoice and invoice item tables shown below and used the
over(partition) clause to split out the shipping per item.
-- sample tables
declare #Invoice table (InvoiceID int, customerID int, Date datetime, ShippingFee float)
declare #InvoiceItem table (InvoiceItemID int identity, InvoiceID int, ItemDesc varchar(50), Quantity float, ItemPrice float)
-- Example 1
insert #Invoice values(1, 800, getdate(), 20);
insert #InvoiceItem values(1, 'Widget', 1, 10.00)
insert #InvoiceItem values(1, 'Wing Nut', 5, 2.00)
insert #InvoiceItem values(1, 'Doodad', 8, 0.50)
insert #InvoiceItem values(1, 'Thingy', 3, 1.00)
-- Example 2
insert #Invoice values(2, 815, getdate(), 15);
insert #InvoiceItem values(2, 'Green Stuff', 10, 1.00)
insert #InvoiceItem values(2, 'Blue Stuff', 10, 1.60)
-- Example 3
insert #Invoice values(3, 789, getdate(), 15);
insert #InvoiceItem values(3, 'Widget', 10, 1.60)
-- query
select
n.InvoiceID,
n.InvoiceItemID,
n.ItemDesc,
n.Quantity,
n.ItemPrice,
ExtendedPrice = n.Quantity * n.ItemPrice,
Shipping = i.ShippingFee / count(n.InvoiceItemID) over(partition by n.InvoiceID)
from #InvoiceItem n
join #Invoice i on i.InvoiceID = n.InvoiceID
Output:
InvoiceID InvoiceItemID ItemDesc Quantity ItemPrice ExtendedPrice Shipping
1 1 Widget 1 10 10 5
1 2 Wing Nut 5 2 10 5
1 3 Doodad 8 0.5 4 5
1 4 Thingy 3 1 3 5
2 5 Green Stuff 10 1 10 7.5
2 6 Blue Stuff 10 1.6 16 7.5
3 7 Widget 10 1.6 16 15