如何根据条件删除结果以计算平均电影和特定电影

你要

left join

SELECt m.name, AVG(COALESCE(r.rating, 0)) AS avg_ratingFROM movies mLEFT JOIN reviews r     ON m.id = r.movie_id    AND NOT EXISTS (        SELECt 1         FROM blocked b        WHERe b.blocked_cus_id = r.cus_id AND b.cus_id = 1    )WHERe m.id = 2GROUP BY m.id, m.name;