Mysql Rails联合查询
如何在rails/active record中执行联合(外部联接)查询Mysql Rails联合查询,mysql,ruby-on-rails,Mysql,Ruby On Rails,如何在rails/active record中执行联合(外部联接)查询 ... FROM `parents` LEFT JOIN `child` on parents.child_id = child.id UNION ... FROM `parents` RIGHT JOIN `child` on parents.child_id = child.id ORDER BY rate desc, grade desc, date desc; …使用Model.j
...
FROM `parents`
LEFT JOIN `child` on parents.child_id = child.id
UNION
...
FROM `parents`
RIGHT JOIN `child` on parents.child_id = child.id
ORDER BY rate desc, grade desc, date desc;
…使用Model.joins()?目前没有一种使用常规ActiveRecord语法的方法,尽管有人提出了这样的想法: 在这种方法存在之前,您可以使用find_by_sql方法实现您的目标,如下所述: