[DotNetDevelopment] not saving data to mysql

[Dickery1]

i dont know why this code is not saving the data that i am trying to
insert. appreciate any help
MySqlConnection myConnection = new MySqlConnection(CONN);
            MySqlDataAdapter myDataAdapter = new
MySqlDataAdapter(QUERY, myConnection);
            DataTable dt = new DataTable();

            //Open connection
            myConnection.Open();

            try
            {
                //Fill dataset
                myDataAdapter.Fill(dt);

                //Close connection
                myConnection.Close();
                DataTable dtPortfolios = dt;
                DataRow newRow = dtPortfolios.NewRow();
                newRow["symbol"] = "errwerew";
                newRow["quantity"] = 2;
                newRow["cost"] = 4;
                newRow["created_at"] = DateTime.Now;
                dtPortfolios.Rows.Add(newRow);
                dtPortfolios.AcceptChanges();
                myDataAdapter.Update(dt);


            }
            catch (Exception ex)
            {

                //Close connection
                myConnection.Close();

                throw ex;

            }