Question

我有两个独立的 BigQuery 查询，在该查询中，我提取了某个日期的确认病例总数，然后按地区将其分组，并按病例降序排列。

SELECT region, SUM(confirmed_cases) AS total_cases FROM provincedata WHERE date BETWEEN '2020-08-01' AND '2020-08-02' GROUP BY region ORDER BY total_cases DESC
SELECT region, SUM(confirmed_cases) AS total_cases FROM provincedata WHERE date BETWEEN '2020-08-31' AND '2020-09-01' GROUP BY region ORDER BY total_cases DESC

我要计算第一个查询和第二个查询中的total_cases之间的差异，并按区域和降序对分组和顺序进行计算，并按降序进行计算。

Answer 1

以下是用于BigQuery标准SQL

最简单的方法就是重用您已经习惯的查询（而不是重写内容）

#standardSQL
WITH `project.dataset.query1` AS (
  SELECT region, SUM(confirmed_cases) AS total_cases 
  FROM provincedata 
  WHERE DATE BETWEEN '2020-08-01' AND '2020-08-02' 
  GROUP BY region 
), `project.dataset.query2` AS (
  SELECT region, SUM(confirmed_cases) AS total_cases 
  FROM provincedata 
  WHERE DATE BETWEEN '2020-08-31' AND '2020-09-01' 
  GROUP BY region 
)
SELECT region, q1.total_cases - q2.total_cases AS total_cases_difference
FROM `project.dataset.query1` q1 
JOIN `project.dataset.query2` q2
USING(region)
ORDER BY total_cases_difference DESC

Answer 2

这可以通过条件聚合更有效地表达：

select
    region,
    sum(case when date between '2020-08-01' and '2020-08-02' then confirmed_cases else 0 end) total_cases_1,
    sum(case when date between '2020-08-31' and '2020-09-02' then confirmed_cases else 0 end) total_cases_2,
    sum(case when date between '2020-08-01' and '2020-08-02' then confirmed_cases else - confirmed_cases end) diff
from provincedata
where 
    date between '2020-08-01' and '2020-08-02'
    or date between '2020-08-31' and '2020-09-01' 
group by region
order by diff desc

从单独的BigQuery查询中减去列

2 个答案: