ty for the reply but i get this error Syntax error (missing operator) in query expression 'SUM(Accessory_Table.Qty * Accessory_Table.Cost) FROM Stock_Table INNER JOIN Accessory_Table ON Stock_Table.StkCode = Accessory_Table.StkCode'. this is my actual code "UPDATE Stock_Table " & _ "SET StkCost = SUM(Accessory_Table.Qty * Accessory_Table.Cost) " & _ "FROM Stock_Table " & _ "INNER JOIN Accessory_Table " & _ "ON Stock_Table.StkCode = Accessory_Table.StkCode" maybe UPDATE and SUM doesnt really work together in access?