kwatch https://blog.hatena.ne.jp/kwatch/ kなんとかの日記 https://kwatch.hatenadiary.org/ merb たとえば Book : Author が Many to Many の関係だったとする。このとき「Book.first.authors」を実行すると、「Unknown column 'author_id' in 'field list'」というエラーが出た。 $ merb -i irb> Book.first.authors ~ SELECT `id`, `title`, `author_id` FROM `books` ORDER BY `id` LIMIT 1 ~ Unknown column 'author_id' in 'field list' (mysql_error_code=00… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fkwatch.hatenadiary.org%2Fentry%2F20081215%2F1229355033" title=" DataMapper で「Unknown column &#39;XXX_id&#39; in &#39;field list&#39;」というエラーが出たとき - kなんとかの日記" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2008-12-15 00:30:33 rich https://kwatch.hatenadiary.org/entry/20081215/1229355033 1.0 100%