private void add_btn_Click(object sender, EventArgs e)
{
room_mod addNewRoom = new room_mod();
addNewRoom.ShowDialog();
refresh();
}
private void add_room_btn_Click(object sender, EventArgs e)
{
this.Hide();
room_mod addNewRoom = new room_mod();
addNewRoom.ShowDialog();
this.Show();
DBConnection con = new DBConnection();
string myQuery = $"SELECT room_id FROM room";
con.Reader(myQuery, "room_id", room_combx);
myQuery = $"SELECT room_id FROM room ORDER BY room_id DESC LIMIT 1";
room_combx.SelectedItem = con.Reader(myQuery, "room_id");
}