the name 'connectdb' does not exist in current context c#

Question

I'm trying to make a simple login form in C# with a mysql db but it keep throwing me this error "the name 'connectdb' does not exist in current context". I tried setting it inside, outside everything but it doesn't work then how do i fix it?

class ConnectionClass
{
   public MySqlConnection connectdb;

        public ConnectionClass()
        {
            string host = "192.168.0.19";
            string db = "test-db";
            string username = "root";
            string password = "";
            string connection_string = "datasource =" + host + "; database=" + db + "; port=3336; username =" + username + "; password =" + password + "; SslMode=none;";

            connectdb = new MySqlConnection(connection_string);
        }
    }
    class USER
    {
        public string log_username { set; get; }
        public string log_password { set; get; }
        public Int32 log_role { set; get; }

        public bool User_verification()
        {
            connectdb.Open();
            MySqlDataReader rd;
            bool check = false;
            using (var cmd = new MySqlCommand())
            {
                cmd.CommandText = "SELECT * FROM `users` WHERE username=@user AND password=@pass";
                cmd.CommandType = CommandType.Text;
                cmd.Connection = connectdb;

                cmd.Parameters.Add("@user", MySqlDbType.VarChar).Value = log_username;
                cmd.Parameters.Add("@pass", MySqlDbType.VarChar).Value = log_password;

                rd = cmd.ExecuteReader();

                while (rd.Read())
                {
                    log_role = rd.GetInt32("role");
                }
                connectdb.Close();
            }
            return check;

        }
}