<%@ Page Language="C#" %>
<%@ OutputCache Duration="120" VaryByParam="Group" %>

<script runat="server">
    public static string Left(string param, int length)
    {
        //we start at 0 since we want to get the characters starting from the
        //left and with the specified lenght and assign it to a variable
        string result = param.Substring(0, length);
        //return the result of the operation
        return result;
    } 
    
    protected void Page_Load(object sender, EventArgs e)
    {
        // Clear any previous output from the buffer
        Response.Clear();
        Response.ContentType = "text/xml";
        System.Xml.XmlTextWriter xtwFeed = new System.Xml.XmlTextWriter(Response.OutputStream, Encoding.UTF8);
        xtwFeed.WriteStartDocument();

        // The mandatory rss tag
        xtwFeed.WriteStartElement("rss");
        xtwFeed.WriteAttributeString("version", "2.0");

        // The channel tag contains RSS feed details
        xtwFeed.WriteStartElement("channel");
        xtwFeed.WriteElementString("title", "The Messenger - TransamericaReinsurance.com RSS Feed");
        xtwFeed.WriteElementString("link", "http://www.transamericareinsurance.com");
        xtwFeed.WriteElementString("description", "Knowledge. Experience. Performance. The Power of Insight.");
        xtwFeed.WriteElementString("copyright", "Copyright 2007 Transamerica Occidental Life Insurance Company");

        // Objects needed for connecting to the SQL database
        System.Data.SqlClient.SqlConnection SqlCon;
        System.Data.SqlClient.SqlCommand SqlCom;
        System.Data.SqlClient.SqlDataReader SqlDR;

        // Edit to match your connection string
        SqlCon = new System.Data.SqlClient.SqlConnection(ConfigurationManager.ConnectionStrings["TARe_DBConn"].ToString());

        // Edit to match your stored procedure or SQL command
        SqlCom = new System.Data.SqlClient.SqlCommand("sproc_RSSFeeds", SqlCon);
        SqlCom.Parameters.Add(new System.Data.SqlClient.SqlParameter("@feedName", "messenger"));
        SqlCom.CommandType = System.Data.CommandType.StoredProcedure;

        SqlCon.Open();
        
        SqlDR = SqlCom.ExecuteReader();

        // Loop through the content of the database and add them to the RSS feed
        while (SqlDR.Read())
        {
            xtwFeed.WriteStartElement("item");
            xtwFeed.WriteElementString("title", SqlDR["Title"].ToString());
            xtwFeed.WriteElementString("description", Left(SqlDR["Description"].ToString(), 250)+"...");
            xtwFeed.WriteElementString("link", "http://cnchnw9321/Media/media_associateArticle.aspx?id=" + SqlDR["ID"]);
            xtwFeed.WriteElementString("pubDate", SqlDR["Date"].ToString());
            xtwFeed.WriteEndElement();
        }

        SqlDR.Close();
        SqlCon.Close();

        // Close all tags
        xtwFeed.WriteEndElement();
        xtwFeed.WriteEndElement();
        xtwFeed.WriteEndDocument();
        xtwFeed.Flush();
        xtwFeed.Close();
        Response.End();
    }
</script>

Generates an RSS XML feed from a SQL stored procedure.

Save below as feedname.aspx, modify stored procedure information to match and run.  No seperate markup or cs file necessary, self contained.

This was created from a combination of articles found online.  
RSS Code originally from: http://www.geekpedia.com/tutorial157_Create-an-RSS-feed-using-ASP.NET-2.0.html

C# Left code from: http://www.csharphelp.com/archives4/archive616.html

ASP.NET 2.0 RSS Feed Generator

C#