partial void DeleteCategories(Categories instance);
 partial void InsertCategories(Categories instance);
 partial void UpdateCategories(Categories instance);
        /// <summary>
        /// Writes the test.
        /// </summary>
        /// <param name="repeatTime">
        /// The repeat time.
        /// </param>
        /// <returns>
        /// The write test.
        /// </returns>
        public long WriteTest(int repeatTime)
        {
            var sw = new Stopwatch();
            sw.Reset();
            sw.Start();

            var db = new CategoryDataContext();
            var db3 = new CategoryDataContext();
            var db2 = new CategoryDataContext();
            for (int i = 0; i < repeatTime; i++)
            {
                var cus = new Customers
                    {
                        CustomerID = "test",
                        CompanyName = "company name",
                        ContactName = "contact name",
                        Address = "address"
                    };
                db.Customers.InsertOnSubmit(cus);
                db.SubmitChanges();

                cus.CompanyName = "update name";
                db.SubmitChanges();

                var cat = new Categories { CategoryName = "Widgets", Description = "Widgets are the ……" };
                var newProduct = new Products { ProductName = "Blue Widget", UnitPrice = 34.56M, Categories = cat };

                db.Categories.InsertOnSubmit(cat);
                db.SubmitChanges();

                cat.CategoryName = "testupdated";
                db.SubmitChanges();

                Products p3 = db3.Products.First(c => c.ProductName == "Blue Widget");
                p3.UnitPrice = 15.8M;
                db3.SubmitChanges();

                #region New a datacontent for delete Products

                Products p2 = db2.Products.First(c => c.ProductName == "Blue Widget");
                db2.Products.DeleteOnSubmit(p2);
                db2.SubmitChanges();

                #endregion

                Categories cat2 = db.Categories.First(c => c.CategoryName == "testupdated");

                db.Categories.DeleteOnSubmit(cat2);
                db.SubmitChanges();

                db.Customers.DeleteOnSubmit(cus);
                db.SubmitChanges();
            }

            db.Dispose();
            db2.Dispose();
            db3.Dispose();
            sw.Stop();
            return sw.ElapsedMilliseconds;
        }