ASP.Net ExecuteReader Error: CommandText property has not been initialized

I am getting the following error:

"Executereader:commandtext property has not been initialised".

What is wrong in my code.Here i am exporting the data to a excel.

private void button1_Click(object sender, EventArgs e)
{
    try
    {
        string fileName = String.Empty;
        SaveFileDialog saveFileExcel = new SaveFileDialog();
        saveFileExcel.Filter = "Text files |*.csv|All files (*.*)|*.*";
        saveFileExcel.FilterIndex = 2;
        saveFileExcel.RestoreDirectory = true;
        if (saveFileExcel.ShowDialog() == DialogResult.OK)
        {
            fileName = saveFileExcel.FileName + ".csv";
            CreateCSVFile(getDataTableForRetrieve(), fileName);
        }
    }
    catch (Exception ex)
    {
    }
}
private DataTable getDataTableForRetrieve()
{
    SqlConnection conn = null;
    DataTable dt = new DataTable();
    DataTable dt1 = new DataTable();
    try
    {
        MyConnect myCnn = new MyConnect();
        String connString = myCnn.getConnect().ToString();
        SqlCommand command;
        conn = new SqlConnection(connString);
        command = new SqlCommand();
        conn.Open();
        string type = CmbTopCollection.Text;
        string query = "";
        if (type == "today")
        {
            query = "select userinfo.name, count(EMAIL.ID) as num,userdataloginfo.total_count from companyinfo COMPANY INNER JOIN emailinfo EMAIL ON COMPANY.dataID = EMAIL.DataID inner join userinfo ON COMPANY.userid = userinfo.ID inner join userdataloginfo on userdataloginfo.userid = userinfo.id where date >= DATEADD(day, DATEDIFF(day, 0, GETDATE()), 0) AND date < DATEADD(day, DATEDIFF(day, 0, GETDATE()), 1) group by userinfo.name,userdataloginfo.total_count order by num desc";
        }
        command = new SqlCommand(query, conn);

        SqlDataAdapter da = new SqlDataAdapter(command);
        da.Fill(dt);
        conn.Close();
    }
    catch (Exception e1)
    {
        MessageBox.Show(e1.Message.ToString());
    }
    finally
    {
        if (conn.State == ConnectionState.Open)
            conn.Close();
    }
    return dt;
}
public void CreateCSVFile(DataTable dt, string strFilePath)
{
    StreamWriter sw = new StreamWriter(strFilePath, false, Encoding.GetEncoding("iso-8859-1"));
    string csvStr = "";
    int iColCount = dt.Columns.Count;
    for (int i = 0; i < iColCount; i++)
    {
        sw.Write(dt.Columns[i]);
        if (i < iColCount - 1)
        {
            sw.Write(",");
        }
    }

    sw.Write(sw.NewLine);

    foreach (DataRow dr in dt.Rows)
    {
        for (int i = 0; i < iColCount; i++)
        {
            if (!Convert.IsDBNull(dr[i]))
            {
                csvStr = "\"" + dr[i].ToString().Replace(@"""", "") + "\"";
                //csvStr.Replace(@"""", "");
                sw.Write(csvStr);
            }
            if (i < iColCount - 1)
            {
                sw.Write(",");
            }
        }
        sw.Write(sw.NewLine);
    }
    sw.Close();
    MessageBox.Show("Exporting Completed");

}

Any help will be appreciated.