It makes it a lot easier to troubleshoot if you apply a little formatting to your query, and using a tool such as as Sql Studio should have
red lined the query due to any errors. Especially if you tried running it
select SalesOrder.OrderNo
, ItemMasterFile.Descriptionitem
, OrderDetail.orderqty
, Customer.CustomerName
from OrderDetail
inner join ItemMasterFile on ItemMasterFile.CodeItem =OrderDetail.CodeItem
inner join Customer on Customer.CustomerID =SalesOrder.CustomerID
The first thing you have in your SELECT list is SalesOrder.OrderNo, however; SalesOrder is neither the FROM source nor is it JOINed.
Another tip I recommend is to use
aliases for the table names, it also helps in readability
SELECT s.OrderNo
, i.Descriptionitem
, d.Qty
, c.CustomerName
FROM Sales_Order s
INNER JOIN OrderDetail d ON s.OrderNo = d.OrderNo
INNER JOIN Item_master i ON d.Item_code = i.Item_code
INNER JOIN customer c ON c.CustomerID = s.CustomerID