1
是否可以使用Rail的ActiveRecord格式编写以下查询?我已经尝试了十亿种与arel不同的方式,但无法获得相同的结果。将Postgres查询转换为Rails ActiveRecord?
SELECT topic_id, count(*) as total
FROM questions_topics
WHERE question_id IN (
SELECT id
FROM questions
WHERE user_id = 1000
UNION ALL
SELECT questions.id
FROM questions JOIN answers ON (questions.id = answers.question_id)
WHERE answers.user_id = 1000
)
GROUP BY topic_id
ORDER BY total DESC;
您是否有像QuestionTopic和其他相关模型? – zishe
我会先将它转换为EXISTS(...)或EXISTS(...)形式,这可能会比UNION更有效率。 – joop
也许这次演讲会帮助你理解Arel:https://www.youtube.com/watch?v=ShPAxNcLm3o它解释了如何将任何SQL查询转换为Arel AST – Hnatt