对子查询 Bigquery 进行分组和平均答案

【问题标题】：Group by and average on subquery Bigquery对子查询 Bigquery 进行分组和平均
【发布时间】：2020-01-08 14:09:17
【问题描述】：

我正在尝试按日期对记录进行分组，并针对该特定日期获取称为延迟的列之一的平均值。我有以下标准 SQL 查询，当我尝试获取表的 avg 和 group by 时，该查询有效但不起作用：


SELECT * 
From 
(
SELECT 'ADS-B Average Latency for Asia' as metric_name, 'Daily' as metric_period_type,
  DATE(timestamp) as metric_date, collection_type, UNIX_SECONDS(ingestion_time) - UNIX_SECONDS(timestamp) as latency
  FROM `analytics.aoi_table` a
  order by metric_date
) table

这是表格：

当我尝试使用下面的 sql 对上表进行 avg 和 group by 时，我收到以下错误：语法错误：预期为“）”但在 [10:3] 获得关键字 GROUP

导致错误的SQL：

#standardSQL

SELECT * 
From 
(
SELECT 'ADS-B Average Latency for Asia' as metric_name,
  DATE(timestamp) as metric_date, collection_type, AVG(UNIX_SECONDS(ingestion_time) - UNIX_SECONDS(timestamp)) as latency
  FROM `ais-data-analysis.customer_analytics.itochu_aoi_table` a
  order by metric_date
  group by metric_date, collection_type
) table

【问题讨论】：

标签： sql group-by google-bigquery average

【解决方案1】：

您的group by 和order by 乱序。另外，你不需要子查询：

select 'ADS-B Average Latency for Asia' as metric_name,
       DATE(timestamp) as metric_date, collection_type, AVG(UNIX_SECONDS(ingestion_time) - UNIX_SECONDS(timestamp)) as latency
from `ais-data-analysis.customer_analytics.itochu_aoi_table` a
group by metric_date, collection_type
order by metric_date

【讨论】：

【解决方案2】：

order by 子句在 group by 子句之后。此外，无需包装您的查询，您可以这样做：

SELECT 
    'ADS-B Average Latency for Asia' as metric_name,
    DATE(timestamp) as metric_date, 
    collection_type, 
    AVG(UNIX_SECONDS(ingestion_time) - UNIX_SECONDS(timestamp)) as latency
FROM `ais-data-analysis.customer_analytics.itochu_aoi_table` a
GROUP BY metric_date, collection_type
ORDER BY metric_date, collection_type

【讨论】：