the result of the query inserted in an array/list with distinction of 2 columns.?

reppelz

ex.
A 01/01/2011

B 01/01/2011

C 01/01/2011

D 01/01/2011

A 01/02/2011

B 01/02/2011

D 01/02/2011

A 01/03/2011

D 01/03/2011

The query were planning to use ?

SELECT DISTINCT Alphabets,
dateReceive FROM
database
ORDER BY Alphabets

using List

Our expected output

[{A,B,C,D},{A,B,D},{A,D}

Source code:

using (var conn = new SqlConnection("Data Source=SERV-PC\MSQLSERVER;Initial Catalog=MyDatabase;Integrated Security=True"))
{

            using (var cmd = new SqlCommand())
            {
                cmd.Connection = conn;
                cmd.CommandText = "SELECT DISTINCT [ColumnA], [DateReceive] FROM [MyDatabase].[dbo].[dummy] WHERE [ColumnA]=@loca  AND [DateReceive] BETWEEN '01/01/2013' and '01/07/2013' ";
                cmd.Parameters.AddWithValue("@loca", DropDownList1.SelectedValue.ToString());
                conn.Open();
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {

                        var tmp = reader["ColumnA"];
                        if (tmp != DBNull.Value)
                        {

                            ListBox1.Items.Add(reader["ColumnA"].ToString());
                        }
                    }
                }
            }
        }

hope anyone here can help us
thanks