var goods = from g in db.GOODs 
                        select new
                        {
                            g.ID,
                            g.SKU,
                            g.HAVE,
                            g.PRICE1,
                            g.PRICE2,
                            PRODUCER_NAME = g.NAME,
                            category = g.GOODS_AND_CATEGORies.SingleOrDefault(t => t.GOOD_ID == g.ID).CATEGORIES_GOOD.ToList<CATEGORIES_GOOD>(),
                            COTEGORY = ""
                        };
            foreach (var t in goods)
            {
                foreach (var p in t.category)
                {
                    t.COTEGORY += p.NAME+", ";
                }
            }
            GoodsGrid.DataSource = goods;