public async Task <BookDto> GetByIdAsync(long id)
{
var sql_ = Db.NewSql();
sql_.Line("SELECT * FROM Book WHERE Id=@id");
var book = await Db.FirstOrDefaultAsync <BookDto>(sql_, new { id });
NotFoundException.ThrowIf(book == null);
sql_.Clear();
sql_.Line("SELECT T.*")
.Line("FROM BookTag BT")
.Line("LEFT JOIN Tag T ON T.Id=BT.TagId")
.Line("WHERE BT.BookId=@id");
book.Tags = (await Db.QueryAsync <Tag>(sql_, new { id })).ToList();
return(book);
}