Исключение в DataGridView:



System.Data.NoNullAllowedException: В столбце "NumID" не допускаются значения равные nulls.

   в System.Data.DataColumn.CheckNullable(DataRow row)

   в System.Data.DataTable.RaiseRowChanging(DataRowChangeEventArgs args, DataRow eRow, DataRowAction eAction, Boolean fireEvent)

   в System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Boolean suppressEnsurePropertyChanged, Int32 position, Boolean fireEvent, Exception& deferredException)

   в System.Data.DataTable.InsertRow(DataRow row, Int64 proposedID, Int32 pos, Boolean fireEvent)

   в System.Data.DataView.FinishAddNew(Boolean success)

   в System.Data.DataRowView.EndEdit()

   в System.Windows.Forms.CurrencyManager.EndCurrentEdit()

   в System.Windows.Forms.DataGridView.DataGridViewDataConnection.OnRowValidating(DataGridViewCellCancelEventArgs e)



Для замены этого окна по умолчанию обработайте событие DataError.

CREATE TABLE [dbo].[Num](
	[NumID] [uniqueidentifier] ROWGUIDCOL  NOT NULL,
	[code] [nvarchar](50) NOT NULL,
	[Description] [nvarchar](255) NOT NULL,
	[PrintDescription] [nvarchar](255) NOT NULL,
 CONSTRAINT [PK_Num] PRIMARY KEY CLUSTERED 
(
	[NumID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[Num] ADD  CONSTRAINT [DF_Num_NumID]  DEFAULT (newid()) FOR [NumID]
GO