如何在 where 子句中过滤 select 语句中包含 count/distinct/case/when 的列

Question

在 hadoop 上使用 SQL。

我有一个 ID 列表，我试图在其中计算 2 种不同的客人评论数据点的总数。对于guest_review_1，我已退回总数。对于guest_review_2，我将总数分为 5 个范围。

我正在努力的是在 guest_review_1 的 where 子句中设置一个过滤器，其中我不包括总数少于 5 个的属性。

任何解决方法的想法？嵌套的 Select 语句可能吗？

包含以下查询示例：

Select 
id,
count(distinct guest_review_1) as "Guest_Reviews",
count(distinct(case when guest_review_2 < 1 then guest_review_1 end)) as Group1,
Count(distinct(case when guest_review_2 >=2 AND guest_review_2 <3 then guest_review_1 end)) as Group2,
From  table_name
Where
guest_review_2 IS NOT NULL
AND guest_review_1 >=5
AND date BETWEEN '2017-01-01' AND '2017-01-31'
Group By id

Answer 1

我不完全确定您的示例查询中 group_1 和 group_2 聚合的含义。但是，您问题的本质似乎是关于如何根据聚合函数 (count) 的结果过滤结果集，而不是过滤单个输入行的值。 Apache Hive 通过使用 SQL HAVING 子句来支持这一点。

在以下示例中，输入关系包含 6 行 id 设置为 1 和 4 行 id 设置为 2。该查询包括子句HAVING guest_reviews >= 5。由于HAVING 子句，结果集只包含id 和1 的行。没有将id 设置为2 的输出行。

WITH table_name AS (
    SELECT 1 AS id, 1 AS guest_review_1, 1 AS guest_review_2 UNION ALL
    SELECT 1 AS id, 2 AS guest_review_1, 2 AS guest_review_2 UNION ALL
    SELECT 1 AS id, 3 AS guest_review_1, 3 AS guest_review_2 UNION ALL
    SELECT 1 AS id, 4 AS guest_review_1, 4 AS guest_review_2 UNION ALL
    SELECT 1 AS id, 5 AS guest_review_1, 5 AS guest_review_2 UNION ALL
    SELECT 1 AS id, 6 AS guest_review_1, 6 AS guest_review_2 UNION ALL
    SELECT 2 AS id, 1 AS guest_review_1, 1 AS guest_review_2 UNION ALL
    SELECT 2 AS id, 2 AS guest_review_1, 2 AS guest_review_2 UNION ALL
    SELECT 2 AS id, 3 AS guest_review_1, 3 AS guest_review_2 UNION ALL
    SELECT 2 AS id, 4 AS guest_review_1, 4 AS guest_review_2
)
SELECT
    id,
    count(DISTINCT guest_review_1) AS guest_reviews,
    count(DISTINCT(CASE WHEN guest_review_2 < 1 THEN guest_review_1 END)) AS group_1,
    count(DISTINCT(CASE WHEN guest_review_2 >= 2 AND guest_review_2 < 3 THEN guest_review_1 END)) as group_2
FROM table_name
WHERE guest_review_2 IS NOT NULL
GROUP BY id
HAVING guest_reviews >= 5
;