SqlDataAdapter mydataAdapter = new SqlDataAdapter();
                string vSQLRefresh = "SELECT * from dbo.usermaster";
                mydataAdapter.SelectCommand = new SqlCommand(vSQLRefresh, cnn);

                DataTable table = new DataTable();
                mydataAdapter.Fill(table);

                BindingSource bSource = new BindingSource();
                bSource.DataSource = table;
                dataGridView1.DataSource = bSource;
                dataGridView1.Refresh();