June 2018
Beginner to intermediate
210 pages
5h 12m
English
Content preview from Apache Hive Essentials - Second Edition
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Aggregation condition
Since v0.7.0, HAVING has been added to support the conditional filtering of aggregation results directly. By using HAVING, we can avoid using a subquery after the GROUP BY statement. See the following example:
> SELECT > gender_age.age > FROM employee> GROUP BY gender_age.age > HAVING count(*)=1;+----------------+| gender_age.age |+----------------+| 27 || 30 || 35 || 57 |+----------------+4 rows selected (25.829 seconds)> SELECT > gender_age.age, > count(*) as cnt -- Support use column alias in HAVING, like ORDER BY> FROM employee > GROUP BY gender_age.age HAVING cnt=1; +----------------+-----+| gender_age.age | cnt |+----------------+-----+| 27 | 1 || 30 | 1 || 35 | 1 || 57 | 1 |+----------------+-----+ 4 rows selected ...
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