public SqlDataReader  GetCategories() {     string connectionString =     ConfigurationManager.ConnectionStrings["SQLConnString"].ConnectionString;     SqlConnection conn = new SqlConnection(connectionString);     conn.Open();

    string cmdString = "SELECT Name FROM Category";     SqlCommand cmd = new SqlCommand(cmdString, conn);     SqlDataReader rdr = cmd.ExecuteReader();

    //这个怎么办呢？不加，不规范；加呢？阅读器关闭时 FieldCount 的尝试无效。     conn.Close();

    return rdr; }