public static int InsertRelCategory(int productID, int categoryID)
 {
     var relCat = new ProductRelCategory()
     {
         ProductID = productID,
         CategoryID = categoryID
     };
     db.ProductRelCategories.InsertOnSubmit(relCat);
     db.SubmitChanges();
     
     return 1;
 }
 partial void DeleteProductRelCategory(ProductRelCategory instance);
 partial void UpdateProductRelCategory(ProductRelCategory instance);
 partial void InsertProductRelCategory(ProductRelCategory instance);
		private void detach_ProductRelCategories(ProductRelCategory entity)
		{
			this.SendPropertyChanging();
			entity.Product = null;
		}
		private void attach_ProductRelCategories(ProductRelCategory entity)
		{
			this.SendPropertyChanging();
			entity.Category = this;
		}