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; }