Traverse Columns Without Knowing Names/fields???

I've called a resultset from SQL Server
using an SQL Selection. I need to iterate over that entire result set
(200+ columns/fields) and all I need are the random numbers contained
in any of the rows/columns. I don't want to have to name each
field/column and then use an if > 0 statement.

Isn't there
some way to generically loop through the column's by index or something
instead of their field name so I can just use an integer loop to walk
the dataset? I know there is I've done it about 5 years ago. The
question is how do you do it in C#?

SqlConnection thisConn = new SqlConnection(ConfigurationManager.ConnectionStrings["SQLQuery"].ConnectionString);
        SqlCommand thisCmd = new SqlCommand("Command String", thisConn);
        thisCmd.CommandText = "Select * from SelectionsByCountry where [" + DropDownList1.SelectedItem.ToString() + "] > '0'";
        thisConn.Open();
       
        SqlDataReader thisReader = null;
        thisReader = thisCmd.ExecuteReader(CommandBehavior.CloseConnection);

        while (thisReader.Read())
        {
            DropDownList2.Items.Add(thisReader["System"].ToString().Trim());

/**
* There are 200+ columns left I want to walk over using a loop structure of some sort. How do I do that?
*/
           
        }

- Rex