Ruby on rails 3 两个表上具有联接和条件的活动记录查询

我想使用活动记录执行此查询，以便使查询不会被注入。DB是Postgresql。RubyonRails 3.2.11

 def find_possible_duplicates(last_name, date_of_birth, organisation_id)
    find_by_sql( 'select c.* from clients c' +
                 ' join locations l on c.location_id = l.id' +
                 " where c.last_name ILIKE #{last_name}" +
                 " and c.date_of_birth = #{date_of_birth}" +
                 " and l.organisation_id = #{organisation_id}" 
 end        

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感谢您的任何帮助

以下是活动记录查询：

 Client.select('clients.*').
 joins('join locations on clients.location_id=locations.id').
 where('last_name like ? and date_of_birth =? and organisation_id = ?',last_name,date_of_birth,organisation_id)