多对多关联数据存储ROR

Sku MODEL :

class Sku < ActiveRecord::Base

  has_and_belongs_to_many :records,
      :delete_sql=>'DELETE FROM skus_records WHERE sku_id= \'#{id}\' AND record_id = #{record.id}',
      :before_remove=>:record_removed_info,
      :insert_sql =>'insert into skus_records (sku_id,record_id,createdOn) values (\'#{id}\',#{record.id},now())'

end

Record MODEL :

class Record < ActiveRecord::Base
  has_and_belongs_to_many :skus,
      :delete_sql=>'DELETE FROM skus_records WHERE sku_id= \'#{record.id}\' AND record_id = #{id}',
      :before_remove=>:record_removed_info,
      :insert_sql =>'insert into skus_records (sku_id,record_id,createdOn) values (\'#{record.id}\',#{id},now())' 

end

以下是在Record 模型中，指定一条记录，并把此记录与多个sku信息关联。

sku_models = []
[1,2,3,4,5,6,7].each do |id|
sku = Sku.find_by_skuid(id)
sku_models << sku unless sku.nil?
end
record_m = Record.find(224)
record_m.skus.concat(sku_models) unless record_m.nil?   # 向 record 224 的记录添加多个sku的信息。

record_m.skus.delete(sku_models)  # 从 record 224中删除指定的sku的对应关系。