If e.DataCol.Name = "订单号" Then
If e.NewValue Is Nothing Then
MessageBox.Show("订单号不允许为空!")
e.Cancel = True
Else
Dim dr As DataRow
dr = e.DataTable.Find("订单号 = '" & e.NewValue & "'")
If dr IsNot Nothing Then
MessageBox.Show("此订单号已经存在!")
e.Cancel = True
End If
End If
End If