Mysql sql语句的接受率

我有一个“建议”表，其结构如下：

id(suggest_id) | author_id | accepted(true/false)

我想按最大接受率订购，例如：

Jack had 10 suggests and he accepted 5 (50% acceptance rate)
John had 20 suggests and he accepted 5 (25% acceptance rate)
Steve had 10 suggests and he accepted 8 (80% acceptance rate)

这将返回：史蒂夫，杰克和约翰

我认为它可能必须有两个SQL查询，一个用于建议数，另一个用于

accepted=true

也许一个查询就可以完成

---

我使用的是rails，所以它也可以由rails来完成。

取决于您如何表示接受（真/假）的内容，例如

select author_id, 
    sum(case when accepted ='true' then 1 else 0 end), 
    100.0*sum(case when accepted ='true' then 1 else 0  end)/count(*)
from yourtable
group by author_id
order by 100.0*sum(case when accepted ='true' then 1 else 0 end)/count(*) desc

---

取决于你是如何表达被接受（真/假）的，比如

select author_id, 
    sum(case when accepted ='true' then 1 else 0 end), 
    100.0*sum(case when accepted ='true' then 1 else 0  end)/count(*)
from yourtable
group by author_id
order by 100.0*sum(case when accepted ='true' then 1 else 0 end)/count(*) desc

---

您也可以尝试使用纯ruby：

@authors_by_acceptance_rate = Array.new
@authors = Author.all
@authors.each do |author|
  @suggests = Suggest.find_by_author_id(author.id)
      accepted = 0
  @suggests.each do |suggest|
    if suggest.accepted
      accepted = accepted + 1
    end
  end
  acceptance_rate = accepted/@suggests.count
  @authors_by_acceptance_rate.push('name' => @author.name, 'accepted' =>     acceptance_rate)   
end
return @authors_by_acceptance_rate

---

我还没有测试过这个，所以不能保证它正常工作…

您也可以尝试使用纯ruby：

@authors_by_acceptance_rate = Array.new
@authors = Author.all
@authors.each do |author|
  @suggests = Suggest.find_by_author_id(author.id)
      accepted = 0
  @suggests.each do |suggest|
    if suggest.accepted
      accepted = accepted + 1
    end
  end
  acceptance_rate = accepted/@suggests.count
  @authors_by_acceptance_rate.push('name' => @author.name, 'accepted' =>     acceptance_rate)   
end
return @authors_by_acceptance_rate

---

我还没有测试过这个，所以不能保证它能正常工作…

使用

HAVING

而不是

WHERE

来过滤聚合。例：

计数（*）>10

谢谢！顺便说一句，GROUP BY必须在使用

HAVING

而不是

WHERE

之前进行筛选以筛选聚合。例：

计数（*）>10

谢谢！顺便说一句，分组前必须