我有下面的代码可以很好地删除记录，但是在尝试使用 after_save 回调将记录插入表中时，什么也不做。
本质上，我正在做的是创建一系列高级关系，这些关系应该从表campaign_category_metro_bids 中创建或删除关系。如果我在 PHPMyAdmin 中运行就没有问题。但是点击并在rails中激活只允许调用第二个回调，after_destroy......
class CampaignMetro < ActiveRecord::Base
belongs_to :campaign
belongs_to :metro
after_destroy :destroy_category_campaign_metro_bid
after_save :create_category_campaign_metro_bid
def create_category_campaign_metro_bid
insert = "INSERT INTO campaign_category_metro_bids (campaign_id,category_id, metro_id, created_at, updated_at)
SELECT e.campaign_id, e.category_id, e.metro_id, NOW(), NOW()
FROM
(SELECT c.campaign_id, c.category_id, c.metro_id
FROM (SELECT a.campaign_id, a.category_id, b.metro_id
FROM campaign_categories a
cross join campaign_metros b
ON a.campaign_id = b.campaign_id) c) e
LEFT JOIN campaign_category_metro_bids d
ON d.campaign_id = e.campaign_id and
d.category_id = e.category_id and
d.metro_id = e.metro_id
WHERE d.campaign_id is null and
d.category_id is null and
d.metro_id is null;"
ActiveRecord::Base.connection.execute(insert)
end
def destroy_category_campaign_metro_bid
delete="DELETE d.*
FROM campaign_category_metro_bids d
LEFT JOIN
(SELECT c.campaign_id, c.category_id, c.metro_id
FROM (SELECT a.campaign_id, a.category_id, b.metro_id
FROM campaign_categories a
cross join campaign_metros b
ON a.campaign_id = b.campaign_id) c) e
ON d.campaign_id = e.campaign_id and
d.category_id = e.category_id and
d.metro_id = e.metro_id
WHERE e.campaign_id is null and
e.category_id is null and
e.metro_id is null;"
ActiveRecord::Base.connection.execute(delete)
end
end
我怎样才能让它工作？