区分ActiveRecord::Base.connection mysql加入查询结果的方法？答案

【问题标题】：Way to differentiate ActiveRecord::Base.connection mysql joined query result?区分ActiveRecord::Base.connection mysql加入查询结果的方法？
【发布时间】：2018-05-22 08:25:28
【问题描述】：

我的查询：

records = ActiveRecord::Base.connection.execute("SELECT * FROM leads WHERE leads.status=1 AND leads.account_id=1 AND leads.id > 253380")

结果：

    records.first
[253381, 1, "first", "king", "CEO", "Jewelry & Toys", "11111", "22222", nil, nil, nil, nil]

    records.fields
["id", "account_id", "first_name", "last_name", "job_title", "department", "work_number", "mobile_number", "address", "city", "state", "zipcode"]

到目前为止一切都很好，但现在当我离开查询时，如下所示：

records = ActiveRecord::Base.connection.execute("SELECT * FROM leads LEFT JOIN lead_details ON lead_details.id=leads.id AND lead_details.account_id = leads.account_id WHERE leads.status=1 AND leads.account_id=1 AND leads.id > 253380")

结果：

    records.first
[253381, 1, "first", "king", "CEO", "Jewelry & Toys", "11111", "22222", nil, nil, nil, nil, nil, nil, nil, nil]

    records.fields
["id", "account_id", "first_name", "last_name", "job_title", "department", "work_number", "mobile_number", "address", "city", "state", "zipcode", "id", "account_id", "stars", "score"]

注意：最后一个数组"id", "account_id", "stars", "score"是连接表的列

当我尝试将记录转换为哈希第二个id，account_id 将覆盖第一个id，account_id，结果将是这样的

{"id"=>nil,
   "account_id"=>nil,
   "first_name"=>"first",
   "last_name"=>"king",
   "job_title"=>"CEO",
   "department"=>"Jewelry & Toys",
   "work_number"=>"11111",
   "mobile_number"=>"22222",
   "address"=>nil,
   "city"=>nil,
   "state"=>nil,
   "zipcode"=>nil,
   "stars"=>nil,
   "score"=>nil
  }

如何解决这种数据覆盖问题？有什么方法可以根据表名或其他东西将查询结果分区为嵌套数组？

【问题讨论】：

我认为覆盖是因为#to_hashugar。在调用#to_hashugar 之前，你能展示一下llead 的样子吗？
@maicher - [253381, 1, 'first', 'king', 'CEO', 'Jewelry & Toys', '11111', '22222', nil, nil, nil, nil,无，无，无，无]
在上面的评论中 - 最后 4 个 nil 是lead_details 表。 Lead_details 表有列 - id、account_id、stars、score。因此，由于lead_details 列（id，account_id）被覆盖。有什么方法可以在连接时根据表区分 mysql2 查询结果？？

标签： mysql ruby-on-rails ruby activerecord

【解决方案1】：

所以如果我理解正确的话，第二个表中的列会覆盖第一个表中的列。

我建议不要选择不需要的列。

您可以通过在 SQL 中明确定义要加载第二个表中的哪些列来实现：“stars”和“score”。

"SELECT leads.*, lead_details.stars, lead_details.score FROM leads LEFT JOIN lead_details ON lead_details.id=leads.id AND lead_details.account_id = leads.account_id WHERE leads.status=1 AND leads.account_id=1 AND leads.id > 253380"

【讨论】：

感谢您的回复@maicher。但问题是列数非常大，每张表接近 43，所以我不应该那样做。