public IEnumerable <Hyperlink> GetHrefs(long bookId)
{
return(DB.ExecuteReader("select href,name from book_href,hyperlink where book_href.book_id=? and book_href.hyperlink_id=hyperlink.id", bookId)
.ForEach(reader => new Hyperlink(reader.GetString(0), reader.GetString(1))));
}