组合两个多个 bigquery SELECT FROM 语句

Question

我对 BigQuery 和 SQL 有点陌生，所以我遇到的部分困难可能是我不知道如何描述我遇到的问题，以至于能够搜索答案，但我有看起来所以请温柔。

我想要做的是计算满足一组条件的唯一用户 ID 的总数，然后除以唯一用户 ID 的总数。

例如，要计算所有购买的唯一用户：

SELECT count(userId) 
FROM (SELECT userId 
FROM (FLATTEN([table1], user_attribute)) 
WHERE event_value > 0 and event_parameters.Name = "SKU" 
GROUP BY userId ORDER BY userId)

并计算唯一用户的总数

 SELECT count(userId) 
 FROM (SELECT userId 
 FROM (FLATTEN([table1], user_attribute)) 
 GROUP BY userId ORDER BY userId)

我试图将查询写为

SELECT buyers/total 
    FROM (SELECT COUNT(userId) AS buyers 
    FROM (SELECT userId 
    FROM (FLATTEN([table1], user_attribute)) 
    WHERE event_value > 0 and event_parameters.Name = "SKU" 
    GROUP BY userId ORDER BY userId), 
COUNT(userId) as total
    FROM (SELECT userId 
    FROM (FLATTEN([table1], user_attribute)) 
    GROUP BY userId ORDER BY userId))

但它不起作用。我知道我在做一些根本错误的事情，但我不确定它是什么。我将不胜感激任何帮助。

Answer 1

您可以像这样计算不同的用户：

SELECT
  EXACT_COUNT_DISTINCT(userId) as buyers
FROM (FLATTEN([table1], user_attribute))
WHERE
  event_value > 0
  AND event_parameters.Name = "SKU"

连接它们的一种方法是添加一个静态标量值并将其用于连接：

SELECT
  buyers/total
FROM (
  SELECT
    EXACT_COUNT_DISTINCT(userId) AS buyers,
    1 AS scalar,
  FROM (FLATTEN([table1], user_attribute))
  WHERE
    event_value > 0
    AND event_parameters.Name = "SKU") a
JOIN (
  SELECT
    COUNT(userId) AS total,
    1 AS scalar,
  FROM (FLATTEN([table1], user_attribute)) ) b
ON
  a.scalar=b.scalar