private void btnNext_Click(object sender, EventArgs e)
{
var db = new dbprovider();
var room_id = db.SqlExec($"SELECT uid FROM rooms WHERE room_number = {guests_to_add[0].roomN}")[0][0];
for (int i = 0; i < guests_to_add.Count(); i++)
{
db.SqlExec($"INSERT INTO guests(name, surname, patronymic, used_room_id, date_of_arrival, date_of_leaving) VALUES('{guests_to_add[i].name}', '{guests_to_add[i].surname}', '{guests_to_add[i].patronymic}', {room_id}, GETDATE(), GETDATE())");
}
var res = MessageBox.Show("Заддные успешно занесены", "Успешно", MessageBoxButtons.OK, MessageBoxIcon.Information);
if (res == DialogResult.OK)
{
this.Close();
}
}