将数据库存储的附件写到文件夹上面

SqlConnection conn = new SqlConnection("server=.;uid=sa;pwd=123;database=am89resource");
                    conn.Open();
                    SqlCommand cmd = new SqlCommand("", conn);
                    cmd.CommandText = "select * from picture where id='0331010009'";

                    SqlDataReader dr = cmd.ExecuteReader();
                    if (dr.Read())
                    {
                        byte[] bytes = (byte[])dr["img"];
                        FileStream fs = new FileStream(Server.MapPath("//img//1.gif"), FileMode.Create, FileAccess.Write);
                        fs.Write(bytes, 0, bytes.Length);
                        fs.Flush();
                        fs.Close();
                    }
                    conn.Close();