private void rroombutton_Click(object sender, EventArgs e)
{
roomdataGridView.DataSource = null;
roomdataGridView.Rows.Clear();
List <Room> rlist = da.roomdatagrid();
foreach (var item in rlist)
{
roomdataGridView.Rows.Add(item.Roomno, item.RoomType, item.RoomCost, item.RoomStatus);
}
roomsearchcomboBox.Items.Clear();
roomsearchcomboBox.Items.Add("Roomno");
roomsearchcomboBox.Items.Add("Roomtype");
roomsearchcomboBox.Items.Add("Roomcost");
roomsearchcomboBox.Items.Add("Roomstatus");
roomsearchcomboBox.Text = "";
roomsearchtextBox.Text = "";
rtabControl.SelectedTab = rroomtab;
}