private void AddRoomButton_Click(object sender, EventArgs e)
{
string roomGUID = Guid.NewGuid().ToString().ToUpper();
string floorGUID_fk = FloorListBox2.SelectedValue.ToString();
string roomTypeGUID = RoomTypeListBox2.SelectedValue.ToString();
string roomNumber = Convert.ToString(RoomNumberTextBox.Text);
SqlConnection mySqlConnection = new SqlConnection(connectionString);
mySqlConnection.Open();
SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
mySqlCommand.CommandText = "INSERT INTO Rooms(roomGUID,floorGUID_fk,roomTypeGUID_fk,roomNumber) VALUES('" +
roomGUID + "','" +
floorGUID_fk + "','" +
roomTypeGUID + "','" +
roomNumber + "')";
mySqlCommand.ExecuteNonQuery();
mySqlConnection.Close();
PopulateRoomListBox();
RoomNumberTextBox.Text = "";
RoomNumberTextBox.Focus();
}