在 bigquery 中查询多个数据集中的表时遇到问题答案

【问题标题】：Trouble querying tables in multiple datasets in bigquery在 bigquery 中查询多个数据集中的表时遇到问题
【发布时间】：2020-05-25 16:52:59
【问题描述】：

我正在尝试从两个不同的数据集中查询两个 bigquery 表以获取 2 个单独的列。我都尝试过联合和加入，但他们没有给我我需要的东西。以下是我尝试过的查询

with abagrowth as (
SELECT
  session abas,
  term abat,
  COUNT(distinct studentid) AS acount,
  ROUND(100 * (COUNT(distinct studentid) - LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session)) / LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session),0) || '%' AS agrowth
FROM
  aba.abaresult
GROUP BY
  1,
  2
ORDER BY
  1,
  2),

bidagrowth as (
SELECT
  session bidas,
  term bidat,
  COUNT(distinct studentid) AS bcount,
  ROUND(100 * (COUNT(distinct studentid) - LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session)) / LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session),0) || '%' AS bgrowth
FROM
  bida.bidaresult
GROUP BY
  1,
  2
ORDER BY
  1,
  2)

select abas, agrowth from abagrowth
union all
select bidas, bgrowth from bidagrowth

数据集与此类似

name  subject  session      totalscore
-------------------------------------------
jack  maths    2013/2014         70
jane  maths    2013/2014         65
jill  maths    2013/2014         80
jack  maths    2014/2015         72
jack  eng      2014/2015         87
jane  science  2014/2015         67
jill  maths    2014/2015         70
jerry eng      2014/2015         70
jaasp science  2014/2015         85

我要获取的表格应该是这种格式或类似的格式

session    agrowth  bgrowth
2013/2014   null     null
2014/2015   10%       11%
2015/2016   5%        2%

上面的数字是假设的，例如缘故。

问题

bigquery 可以做到这一点吗？
如果是，如何实现？

谢谢

【问题讨论】：

标签： google-bigquery analytics

【解决方案1】：

关于数据集。是的，您可以查询两个数据集。查看this answer。基本上，您只需要指明您正在使用的项目（可选）、数据集和表即可。

对于您想要获取的数据。您可以使用 JOIN 而不是 UNION 来实现它。按会话加入表将允许您每个会话有一行。然后您可以选择要包含在 SELECT 中的列。

WITH abagrowth AS (
SELECT
  session,
  term abat,
  COUNT(distinct studentid) AS acount,
  ROUND(100 * (COUNT(distinct studentid) - LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session)) / LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session),0) || '%' AS agrowth
FROM
  aba.abaresult
GROUP BY
  1,
  2
ORDER BY
  1,
  2),

bidagrowth AS (
SELECT
  session,
  term bidat,
  COUNT(distinct studentid) AS bcount,
  ROUND(100 * (COUNT(distinct studentid) - LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session)) / LAG(COUNT(distinct studentid), 1) OVER (ORDER BY session),0) || '%' AS bgrowth
FROM
  bida.bidaresult
GROUP BY
  1,
  2
ORDER BY
  1,
  2)

SELECT aba.session, aba.agrowth, bida.bgrowth
   FROM abagrowth aba
   JOIN bidagrowth bida
        ON aba.session = bida.session

UNION 将两个查询的结果堆叠起来。

【讨论】：