这个LINQ查询有什么问题

var item1 = (from a in db.Item
                         where
                         (a.ItemNo == Item.ItemNo ||  Item.ItemNo==null ) &&
                         (a.StatusId == Item.StatusId || Item.StatusId == 0) &&
                           (a.LocationId == Item.LocationId || Item.LocationId == 0)
                         select a).ToList();

            return View(item1);
var item1 = (from a in db.Item