在 select 子句中排序，以支持多列

发布于 2024-10-31 14:39:31 字数 315 浏览 2 评论 0原文

我想根据以下条件从用户表中选择用户：

user.created
user.sales_count

因此，我想获取所有用户，有时按创建日期排序，有时根据 sales_count 排序。我希望能够在 ASC 或 DESC 顺序之间切换。

所有查询都需要有这个 WHERE 子句：

WHERE region = 123

How can I build my active record query to support those order by criteria?

原文

I want to select users from the users table based on:

user.created
user.sales_count

So I want to fetch all users, sometimes ordered by created date, and sometimes based on sales_count. And I want to be able to switch between ASC or DESC order.

All queries need to have this WHERE clause:

WHERE region = 123

How can I build my active record query to support these order by conditions?

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巡山小妖精 2024-11-07 14:39:31

def get_users(options={})
  options[:order_col] ||= "created"
  options[:order_type] ||= ""
  User.where(:region=>123).order("#{options[:order_col]} #{options[:order_type]}")
end

options[:order_col] ||= 实际上是在说：

options[:order_col] = options[:order_col] || ""

的英文意思是将 options[:order_col] 设置为 options[:order_col]（如果已设置），否则 ""。我们可以将 order_type 设置为 "" 因为 SQL 默认情况下会对结果进行 ASC 排序。

例子：

get_users #=> return ordered by created ASC
get_users(:order_col => "sales_count") #=> return order by sales count ASC
get_users(:order_col => "sales_count", :order_type => "DESC") #=> sales_count, DESC
# etc

def get_users(options={})
  options[:order_col] ||= "created"
  options[:order_type] ||= ""
  User.where(:region=>123).order("#{options[:order_col]} #{options[:order_type]}")
end

options[:order_col] ||= is really saying:

options[:order_col] = options[:order_col] || ""

which in english is saying set options[:order_col] to options[:order_col] if set, other wise "". We can set the order_type to "" because SQL will by default order results ASC.

Example:

get_users #=> return ordered by created ASC
get_users(:order_col => "sales_count") #=> return order by sales count ASC
get_users(:order_col => "sales_count", :order_type => "DESC") #=> sales_count, DESC
# etc

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