mysql - 使用 SubQueries 查询 2 个表的总和

Question

我的分析团队使用这样的查询:

SELECT 
    SUM(ul.upload_bandwidth) + SUM(dl.download_bandwidth) AS total 
FROM 
    upload_facts ul, download_facts dl
WHERE 
    ul.date BETWEEN '2011-09-01' AND '2011-09-30' AND 
    dl.date BETWEEN '2011-09-01' AND '2011-09-30';

由于正在发生“加入”，这需要很长时间，超过 12000 秒。

分别从两个表中求和只需几秒钟。我正在考虑将每天的总和放入单独的表格中以加快速度。但是，我相信它应该比这更容易。

我想消除连接并使用子查询来执行此操作，但我不是 100% 确定如何操作。我尝试了以下方法，但没有用。

SELECT 
    (select upload_bandwidth from upload_facts where date 
      BETWEEN '2011-09-01' AND '2011-09-30') 
    + 
    (select download_bandwidth from downloaded_facts where date 
      BETWEEN '2011-09-01' AND '2011-09-30');

Answer 1

SELECT
    (SELECT SUM(`upload_bandwidth`) FROM `upload_facts` WHERE `date` 
      BETWEEN '2011-09-01' AND '2011-09-30')
    +
    (SELECT SUM(`download_bandwidth`) FROM `download_facts` WHERE `date` 
      BETWEEN '2011-09-01' AND '2011-09-30')
AS `total`

应该这样做。