simple active record bulk-updater with different values in a single column Raw

bulk_update.rb

class ActiveRecord::Base
  def self.bulk_update(column, values_by_id)
    ids = values_by_id.keys.join(',')
    query = []
    query << ["UPDATE #{self.table_name} SET #{column}=case id"]
    query << values_by_id.map { |id, count|
      "WHEN #{id} THEN #{count}"
    }
    query << "END"
    query << "WHERE id IN (#{ids})"
    query = query.join("\n")
    self.connection.execute query
  end
end