how to save to excel file from varbinary column

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C#

ASP.NET

I tried the below c# code to write my file table content(file stream -varbinary column) to one excel file. It is downloading the contents to excel file. But i need to save the excel file to the predefined path only. No need to download or open the file.

using (SqlDataReader rdr = DAL.executeQuery(sql, _params))
           {
               if (rdr.Read())
               {
                   Byte[] buffer = (Byte[])rdr["file_stream"];

                   Response.ClearContent();
                   Response.ClearHeaders();
                   Response.ContentType = "application/octet-stream";
                   Response.AddHeader("Content-Disposition", "attachment; filename=" +   rdr["FileNameInClient"].ToString());
                   Response.AddHeader("Content-Type", "application/octet-stream");
                   Response.AddHeader("Content-Length", buffer.Length.ToString());
                   Response.(buffer);
                   Response.Flush();
                   Response.End();
               }
           }

Can anyone please help