最简洁的方式转置SQL表

Question

如何转置此表，所以我有两列，一列显示付费用户的比例和一列显示免费用户的比例。另外，在我的脚本中，有什么方法可以让代码更加简洁，'SQL'就像？我似乎也无法在sqlfiddle中使用select语句创建表，因为我得到一个错误，说它只能在模式屏幕中创建。无论如何，我可以将sql语句嵌入到新表中吗？

我已经创建了sqlfiddle一个脚本，计算不同类型的用户的一些下载指标：http://sqlfiddle.com/#!9/79bea4/1

Answer 1

SELECT df.Date, 
     SUM(CASE WHEN ad.paying_customer = 'No' 
       THEN df.downloads ELSE 0 END)/
     SUM(CASE WHEN ad.paying_customer = 'No' THEN 1 ELSE 0 END) AS `Average Downloads/Free User`, 
     SUM(CASE WHEN ad.paying_customer = 'Yes' 
       THEN df.downloads ELSE 0 END)/
     SUM(CASE WHEN ad.paying_customer = 'Yes' THEN 1 ELSE 0 END) AS `Average Downloads/Paid User` 
FROM 
(
    SELECT date, 
      user_id, 
      SUM(downloads) AS downloads 
    FROM download_facts 
    GROUP BY date, 
      user_id 
) df 
INNER JOIN user_dimension ud 
    ON df.user_id = ud.user_id 
INNER JOIN account_dimension ad 
    ON ud.account_id = ad.account_id 
GROUP BY df.Date 

演示在这里：

SQLFiddle

Answer 2

您可以通过计算平均取下载的总和并除以用户的数量。然后count(distinct)可以得到每个组中的用户：

select df.date, 
     (sum(df.downloads)/
     count(distinct case when ad.paying_customer = 'No' then df.user_id end) 
     ) as avg_free, 
     (sum(df.downloads)/
     count(distinct case when ad.paying_customer = 'Yes' then df.user_id end) 
     ) as avg_paying 
from download_facts df left join 
    user_dimension ud 
    on df.user_id = ud.user_id left join 
    account_dimension ad 
    on ad.account_id = ud.account_id 
group by df.date;