public static bool Authentication(string login, string password)
        {
            try
            {
                using (MySqlConnection con = new MySqlConnection())
                {
                    con.ConnectionString = connectionString;
                    con.Open();
                    using (MySqlCommand com = new MySqlCommand(string.Format("SELECT * FROM Office_workers"), con))
                    {
                        MySqlDataReader dr = com.ExecuteReader();
                        while (dr.Read())
                        {
                            if (dr["Login"].ToString() == login && dr["Password"].ToString() == password)
                            {
                                int ret = int.Parse(dr["id"].ToString());
                                con.Close();
                                return true;
                            }
                        }
                    }
                    con.Close();
                }
            }
            catch (Exception ex){}
            return true;
        }