将两个 sql 查询合并为一个查询，以从 SEDE 中获取单个 table 中最受欢迎的问题和答案

Question

我想从SEDE

中获取最热门的问题

SELECT TOP 10
    'https://whosebug.com/questions/' + CONVERT(VARCHAR, Posts.Id) as url,
    (ViewCount / (SELECT - DATEDIFF(DAY, GETDATE(), CreationDate))) AS ave_views_per_day,
    Body as QUESTION,
    Posts.Id,
    Title
FROM
    Posts
LEFT JOIN 
    PostTags ON Posts.Id = PostTags.PostId
LEFT JOIN 
    Tags ON PostTags.TagId = Tags.Id
WHERE 
    TagName IN ('##tag##')
    AND ViewCount > 10000
ORDER BY 
    ave_views_per_day DESC

我有一个额外的查询来获得给定问题 ID 的最高分答案：

SELECT 
    'https://whosebug.com/questions/' + CONVERT(VARCHAR, Id) as url, HighestScoringAnswer
FROM
    (SELECT TOP 1 
         Id, Body AS HighestScoringAnswer, 
         DENSE_RANK() OVER (ORDER BY Score DESC) Rank 
     FROM 
         (SELECT p.Id, p.ParentId, p.Body, p.Score
          FROM Posts p 
          WHERE p.ParentId = ##QuestionId##) x
     ORDER BY 
         Rank ASC) x

如何组合这些查询，使第二个查询的 ##QuestionId## 来自第一个查询的 Posts.Id，并将生成的 HighestScoringAnswer 列添加到第一次查询的结果？我尝试使用 Union 操作，但无法弄清楚如何将 Id 从一个查询“传递”到另一个查询。

Answer 1

你必须在两个查询（问题和答案）之间做一个 JOIN；不是 UNION（UNION return 来自第一个查询的行加上来自第二个查询的行，不包括重复的行；但是您想要前十个问题和每个问题的得分更高的答案在同一行）。

试试这个查询，我想这就是你要找的查询：

SELECT DISTINCT TOP 10
    'https://whosebug.com/questions/' + CONVERT(VARCHAR, q.Id) as url,
    (q.ViewCount / -DATEDIFF(DAY, GETDATE(), q.CreationDate)) AS ave_views_per_day,
    q.Body as QUESTION,
    q.Id,
    q.Title,
    FIRST_VALUE(a.Body) OVER (PARTITION BY q.id ORDER BY a.Score DESC) AS HighestScoringAnswer
    
FROM Posts q
LEFT JOIN Posts a ON q.id = a.ParentId

WHERE q.PostTypeId = 1 
      AND q.Tags LIKE '%postgresql%'
      AND q.ViewCount > 10000
      
ORDER BY ave_views_per_day DESC;

将两个 sql 查询合并为一个查询，以从 SEDE 中获取单个 table 中最受欢迎的问题和答案

Combining two sql queries into one to get most popular questions & answers in single table from SEDE

sql

dataexplorer