Ruby on rails 如何将SQL转换为Arel？

是否有方法将

匹配

和

与

零件转换为

我在Arel源代码中找不到任何关于它的信息

我使用的是Rails 3

SELECT gigs.time, gigs.channel_id, gigs.song_id, gigs.id, 
  MATCH (songs.title) AGAINST (?) AS song_score,
  MATCH (artists.name) AGAINST (?) AS artist_score
  FROM songs
  INNER JOIN artists ON artists.id = songs.artist_id
  INNER JOIN gigs ON gigs.song_id = songs.id
  WHERE MATCH (artists.name) AGAINST (?) OR
  MATCH (songs.title) AGAINST (?)
  HAVING (artist_score + song_score) > 0

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AFAIK没有Arel

与实施匹配。我的猜测是因为它不是纯SQL，而是特定于MySQL的