Ruby on rails ActiveRecord查询_Ruby On Rails_Activerecord

Ruby on rails ActiveRecord查询

ruby-on-rails activerecord

Ruby on rails ActiveRecord查询,ruby-on-rails,activerecord,Ruby On Rails,Activerecord,有人知道我如何使用ActiveRecord而不是SQL创建此查询吗 @leaderboard = ActiveRecord::Base.connection.execute("SELECT name, street, town, county, avg(volume_used) FROM `DBName`.`events join DBName.households on idhouseholds = events.household_id group by household

有人知道我如何使用ActiveRecord而不是SQL创建此查询吗

@leaderboard = ActiveRecord::Base.connection.execute("SELECT name, street, town, county,        avg(volume_used)  FROM `DBName`.`events
join DBName.households on idhouseholds = events.household_id 
group by household_id
order by volume_used ASC;");

那么

@leaderboard = Event.select([:name,:street,:town,:county,'avg(volume_used) as avg_used']).joins(:households).group('events.household_id').order('volume_used asc')

假设您所说的

idhouses

实际上指的是

houses.id

，并且您希望按照您选择的聚合平均值字段进行排序。

那么

@leaderboard = Event.select([:name,:street,:town,:county,'avg(volume_used) as avg_used']).joins(:households).group('events.household_id').order('volume_used asc')

假设您所说的

idhouses

实际上是指

houses.id

，并且您希望按所选的聚合平均值字段进行排序。

您的ActiveRecord连接将连接到特定的数据库。在运行查询之前，您需要连接到

DBName

（通过在database.yml中指定正确的参数）。ActiveRecord将连接到特定的数据库。在运行查询之前，您需要连接到

DBName