public Customer GetCustomerById(int id)
        {
            using (SqlConnection sqlConn = new SqlConnection(this.connectionString))
            {
                SqlCommand cmd = new SqlCommand("SELECT c.id, c.fname FROM dbo.Customer AS c WHERE c.id =@id", sqlConn);
                cmd.Parameters.Add("@id", SqlDbType.Int).Value = id;
                sqlConn.Open();
                SqlDataReader reader = cmd.ExecuteReader();
                bool isRead = reader.Read();

                return new Customer()
                {
                    CustomerID = reader.GetInt32(0),
                    Name = reader.GetString(1)
                };
            }
        }

        public static bool IsServerConnected(string connectionString)
        {
            using (SqlConnection sqlConn = new SqlConnection(connectionString))
            {
                try
                {
                    sqlConn.Open();
                    return true;
                }
                catch (SqlException)
                {

                    return false;
                }
            }
        }