如何遍历 MySQL 结果集? [英] How can I iterate through a MySQL result set?

问题描述

这是我正在使用的代码:

# 对 .yml 文件中定义的数据库运行查询.# 这是一个 Mysql::result 对象 - http://www.tmtm.org/en/mysql/ruby/@results = ActiveRecord::Base.connection.execute(@sql_query)

在我看来，以下是我为查看值所做的操作:

<%= debug @results %>
输出:#<Mysql2::Result:0x007f31849a1fc0><% @results.each 做 |val|％＞<%=val%><%结束%>输出: ["asdfasdf", 23, "qwefqwef"] ["sdfgdsf", 23, "asdfasdfasdf"]

假设我查询了类似 select * from Person 的内容，然后返回一个结果集，例如:

ID 姓名 年龄1 塞尔吉奥 222 拉兹洛 283 宙斯 47

如何遍历每个值并输出它?

这里的文档没有用，因为我尝试了应该存在的方法，但是解释器给了我一个错误，说这些方法不存在.我是否使用了错误的文档?

http://www.tmtm.org/en/mysql/ruby/

谢谢！

解决方案

如果您使用的是 mysql2 gem，那么您应该获得 mysql2 结果对象，根据文档，您应该能够执行以下操作

results.each do |row|# 方便的是，row 是一个散列# 键是字段，正如你所期望的# 这些值是从 MySQL 中对应的字段类型映射的预构建的 ruby​​ 原语# 这是一只水獭:http://farm1.static.flickr.com/130/398077070_b8795d0ef3_b.jpg结尾

查看文档这里

因此，您可以执行以下操作

<% @results.each do |val|％＞<%= "#{val['id']}, #{val['name']}, #{val['age']}" %><%结束%>

编辑:您似乎指的是错误的文档，请检查 Mysql2 gems 文档.

Here is the code I'm using:

# Run the query against the database defined in .yml file.
# This is a Mysql::result object - http://www.tmtm.org/en/mysql/ruby/
@results = ActiveRecord::Base.connection.execute(@sql_query)

In my View, here's what I do to see the values:

<pre><%= debug @results %></pre>
Outputs: #<Mysql2::Result:0x007f31849a1fc0>

<% @results.each do |val| %>
   <%= val %>
<% end %>
Outputs: ["asdfasdf", 23, "qwefqwef"] ["sdfgdsf", 23, "asdfasdfasdf"]

So imagine I query something like select * from Person, and that returns a result set such as:

ID      Name      Age
1       Sergio    22
2       Lazlow    28
3       Zeus      47

How can I iterate through each value and output it?

The documentation here is not useful because I have tried methods that supposedly exist, but the interpreter gives me an error saying that those methods don't exist. Am I using the wrong documentation?

http://www.tmtm.org/en/mysql/ruby/

Thanks!

解决方案

If you are using mysql2 gem then you should be getting the mysql2 result object and according to the docs you should be able to do the following

results.each do |row|
  # conveniently, row is a hash
  # the keys are the fields, as you'd expect
  # the values are pre-built ruby primitives mapped from their corresponding field types in MySQL
  # Here's an otter: http://farm1.static.flickr.com/130/398077070_b8795d0ef3_b.jpg
end

Checkout the documentation here

So in you case you can do the following

<% @results.each do |val| %>
   <%= "#{val['id']}, #{val['name']}, #{val['age']}" %>
<% end %>

Edit: you seem to be referring to the wrong doc check the Mysql2 gems doc.

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