Database

SELECT 
  coH.PartNumber 
, coH.ManPartNumber 
, SUM(coH.Qty) as TotalQty
, CAST(SUM(coH.Qty * coh.Cost) AS Decimal(10,2)) as TotalCost 
, CAST(SUM(coH.Qty * coh.Price) AS Decimal(10,2)) as TotalPrice 

From cohc In context.Order_History_Cart
Join pi In context.ProductInfo On pi.PartNumber Equals cohc.PartNumber
Join vi In context.ProductInfo_Vendors On vi.VendorID Equals pi.VendorID
Where cohc.OrderDate >= m_startDate _
And cohc.OrderDate <= m_stopDate _
And cohc.PartNumber = p_PartNumber
Select New productItem With
{
   .m_partNumber = cohc.PartNumber,
   .m_manPartNumber = cohc.ManPartNumber,
   .m_totalQty = (From x In context.Order_History_Cart Where x.OrderDate >= m_startDate And x.OrderDate <= m_stopDate And x.PartNumber = p_PartNumber Select x.Qty).Sum(),
   .m_totalCost = (From y In context.Order_History_Cart Where y.OrderDate >= m_startDate And y.OrderDate <= m_stopDate And y.PartNumber = p_PartNumber Select (y.Qty * y.Cost)).Sum(),
   .m_totalPrice = (From z In context.Order_History_Cart Where z.OrderDate >= m_startDate And z.OrderDate <= m_stopDate And z.PartNumber = p_PartNumber Select (z.Qty * z.Price)).Sum(),
   .m_cost = pi.Cost,
   .m_price = pi.Price,