class A< ActiveRecord::Base
def self.select_name
－－－－－－－－不知道怎么写
end
end
class B< ActiveRecord::Base
end
class C< ActiveRecord::Base
end
A：
card:string
is_b:0 or 1
B:
name:string
card:string
C:
realname:string
card:string
实现@test=A.select_name(params[:name])
通过A从B/C表中找到name为params[:name]的模糊搜索（card为关联字段，is_b为判断是否为B表）
万恶的表结构！大神请帮忙！谢谢大家啦！
先看看 SQL 语句怎么写
SELECT a.*
FROM a
LEFT OUTER JOIN b ON (a.card = b.card)
LEFT OUTER JOIN c ON (a.card = c.card)
WHERE (b.name LIKE '%sth%' OR c.name LIKE '%sth%')
转成 AR 的代码
A.joins("LEFT OUTER JOIN b ON (a.card = b.card)")
.joins("LEFT OUTER JOIN c ON (a.card = c.card)")
.where("b.name LIKE ? OR c.name LIKE ?", ['%sth%', '%sth%'])
用 LEFT OUTER JOIN 要注意表数据的量
