Download File That Is Stored In Sql Server Database

Hi,
I have tried to implement file download option. I can download file which is stored in any folder. Code is...

        string filepath = Request.Params["file"].ToString();
        string filename = Path.GetFileName(filepath);
        Response.Clear();
        Response.ContentType = "image/gif";
        Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
        Response.Flush();
        Response.WriteFile(filepath);

This code is working fine. But now I am facing a problem. Files (not the path) are stored in database table. User can download file from the database. How can I do this? The file may be a .txt, .doc, .xls, .jpg or .gif.