问将代码从BGW转换为异步并等待DataTabale/MySQLDataAdapter

EN

private async void button1_Click(object sender, EventArgs e)
{
    button1.Enabled = false;
    var progress = new Progress<string>(update => textBox1.AppendText(update));
    var ds = await Task.Run(() => BackgroundWork(progress));
    dataGridView1.Columns.Clear();
    dataGridView1.DataSource = ds.Tables["StudentNamesAndNumbers"];
    dataGridView1.AutoResizeColumns();
    label1.Text = dataGridView1.Rows.Count.ToString() + " Students";
    button1.Enabled = true;
}

private DataSet BackgroundWork(IProgress<string> progress)
{
    string stdNo = File.ReadAllText("stdNo.txt").Replace(Environment.NewLine, ",");

    const string cs = @"what ever";
    MySqlConnection conn = new MySqlConnection(cs);
    MySqlDataAdapter SQLDataAdapter = new MySqlDataAdapter(); ;
    DataSet ds = new DataSet();
    conn.Open();
    if (progress != null)
        progress.Report(string.Format("MySQL version : {0};", conn.ServerVersion));

    DataTable dt = new DataTable("StudentNamesAndNumbers");
    dt.Columns.Add("Student Name", typeof(string));
    dt.Columns.Add("Student ID", typeof(string));
    dt.Columns.Add("First", typeof(float));
    dt.Columns.Add("Second", typeof(float));
    dt.Columns.Add("Section", typeof(string));
    ds.Tables.Add(dt);

    try
    {
        MySqlCommand SQLcmd = new MySqlCommand();
        SQLcmd = conn.CreateCommand();
        SQLcmd.CommandText = String.Format(@"Select u.firstname as 'Student Name', u.username as 'Student ID'"
                                                + ",( select  score from gradebook_result g , gradebook_evaluation e "
                                                + "where g.user_id = u.user_id "
                                                + "and name = 'First' "
                                                + "and g.evaluation_id = e.id "
                                                + "and e.course_code = c.course_code) as 'First' "
                                                + ",( select  score from gradebook_result g , gradebook_evaluation e "
                                                + "where g.user_id = u.user_id "
                                                + "and name = 'Second' "
                                                + "and g.evaluation_id = e.id "
                                                + "and e.course_code = c.course_code) as 'Second' "
                                                + ", c.course_code as 'Section'"
                                                + "from user u, course_rel_user c "
                                                + "where "
                                                + "u.username in ({0}) "
                                                + "and u.username REGEXP '[0-9]+' "
                                                + "and c.course_code like 'IT102CPLUS%' "
                                                + "and  u.user_id = c.user_id ;", stdNo);

        if (progress != null)
            progress.Report(SQLcmd.CommandText);

        SQLDataAdapter = new MySqlDataAdapter(SQLcmd);
        SQLDataAdapter.Fill(dt);
        dt.DefaultView.Sort = "Section ASC, Student Name ASC";
        var lines = new List<string>();

        string[] columnNames = dt.Columns.Cast<DataColumn>().
                                              Select(column => column.ColumnName).
                                              ToArray();

        var header = string.Join(",", columnNames);
        lines.Add(header);

        var valueLines = dt.AsEnumerable().Select(row => string.Join(",", row.ItemArray));            
        lines.AddRange(valueLines);

        File.WriteAllLines("Export.csv", lines, Encoding.UTF8);
        return ds;
    }
    catch (MySqlException ex)
    {
        if (progress != null)
            progress.Report(string.Format("Error: {0}\n\n", ex.ToString()));
    }
    finally
    {
        if (conn != null)
        {
            conn.Close();
        }
    }
}

    private async void button1_Click(object sender, EventArgs e)
    {
        button1.Enabled = false;
        try
        {
            //Use an async method when there is one available
            string stdNo;
            using (var reader = File.OpenText("Words.txt"))
            {
                stdNo = await reader.ReadToEndAsync();
            }
            stdNo = stdNo.Replace(Environment.NewLine, ",");

            const string cs = @"what ever";
            MySqlConnection conn = new MySqlConnection(cs);
            MySqlDataAdapter SQLDataAdapter = new MySqlDataAdapter(); ;
            DataSet ds = new DataSet();

            //Use Task.Run to call a long running code on another thread
            //If available you should use await conn.OpenAsync();
            await Task.Run(() => conn.Open());
            //You don't need invoke, after an await you are back to the synchronization context
            textBox1.AppendText(string.Format("MySQL version : {0};", conn.ServerVersion));

            DataTable dt = new DataTable("StudentNamesAndNumbers");
            dt.Columns.Add("Student Name", typeof(string));
            dt.Columns.Add("Student ID", typeof(string));
            dt.Columns.Add("First", typeof(float));
            dt.Columns.Add("Second", typeof(float));
            dt.Columns.Add("Section", typeof(string));
            ds.Tables.Add(dt);
            //...
        }
        finally
        {
            button1.Enabled = true;
        }


    }