Question

我有两个SQL查询：

SELECT subreddit, count(subreddit) as count
FROM [fh-bigquery:reddit_comments.all] 
where author="***********" GROUP by subreddit ORDER BY count DESC;

AND

SELECT subreddit, count(subreddit) as count
FROM [redditcollaborativefiltering:aggregate_comments.reddit_posts_all]
where author="***********" GROUP by subreddit ORDER BY count DESC;

我希望能够将这两个查询的结果加入到一个具有相同列的结果中，但是，计数相互相加。有没有简单的方法呢？

Answer 1

您可以使用UNION ALL和其他聚合：

SELECT subredit, SUM(cnt) as cnt
FROM ((SELECT subreddit, count(subreddit) as cnt
       FROM [fh-bigquery:reddit_comments.all] 
       WHERE author = '***********'
       GROUP BY subreddit 
      ) UNION ALL
      (SELECT subreddit, count(subreddit) as cnt
       FROM [redditcollaborativefiltering:aggregate_comments.reddit_posts_all]
       WHERE author = '***********'
       GROUP by subreddit
      )
     ) sc
GROUP BY subreddit
ORDER BY cnt DESC;

Answer 2

对于BigQuery Legacy SQL（我在您的示例中看到您使用），您可以使用以下内容：

#legacySQL
SELECT subredit, SUM(cnt) as cnt
FROM (SELECT subreddit, COUNT(subreddit) as cnt
       FROM [fh-bigquery:reddit_comments.all] 
       WHERE author = '***********'
       GROUP BY subreddit 
      ),
      (SELECT subreddit, COUNT(subreddit) as cnt
       FROM [redditcollaborativefiltering:aggregate_comments.reddit_posts_all] 
       WHERE author = '***********'
       GROUP by subreddit
      )
GROUP BY subreddit
ORDER BY cnt DESC

正如您在此处所见 - 旧版SQL中的逗号用作UNION ALL

以上可以进一步简化

#legacySQL
SELECT subreddit, COUNT(subreddit) as cnt
FROM [fh-bigquery:reddit_comments.all],
  [redditcollaborativefiltering:aggregate_comments.reddit_posts_all]
WHERE author = '***********'
GROUP BY subreddit 
ORDER BY cnt DESC

您可以阅读有关BigQuery Legacy SQL的Comma as UNION ALL的更多信息

加入表格结果Google BigQuery

2 个答案: