private static void SearchDb(Func <string, bool> validator, string query, string searchItem)
        {
            string str = EnterAndValidate(validator, query);

            DbHandler.QueryDb($"select * from Customers where {searchItem}='{str}'");
            Console.ReadKey();
        }
        private static void UpdateCustomer()
        {
            Console.WriteLine("Select userId");
            DbHandler.QueryDb(sql: "execute ListIdAndNames");
            int cId = AskForInt(": ");

            Console.WriteLine("-- Search --");
            Console.WriteLine("1. Update name");
            Console.WriteLine("2. Update email(s)");
            Console.WriteLine("3. Add email(s)");
            Console.WriteLine("4. Update phonenumber(s)");
            Console.WriteLine("5. Add phonenumber(s)");
            Console.WriteLine("6. Back");
            int choice = AskForInt(": ");

            switch (choice)
            {
            case 1:
                SearchDb(Validator.ValidateName, "First name: ", "first_name");
                break;

            case 2:
                SearchDb(Validator.ValidateName, "Last name: ", "last_name");
                break;

            case 3:
                SearchDb(Validator.ValidateEmail, "Email: ", "email_address");
                break;

            case 4:
                SearchDb(Validator.ValidatePhoneNumber, "Phone number: ", "phone_number");
                break;

            default:
                break;
            }
        }
 private static void ListAllCustomers()
 {
     DbHandler.QueryDb(sql: "execute GetAllUsers");
     Console.ReadKey();
 }