March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
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高级
SQL
特性
｜
169
SELECT species, sepal_length_cm,
avg(sepal_length_cm) OVER(PARTITION BY species) AS avgsepal
FROM memory.default.iris;
species | sepal_length_cm | avgsepal
------------+---------------+----------
setosa | 5.1 | 5.006
setosa | 4.9 | 5.006
setosa | 4.7 | 5.006
...
virginica | 6.3 | 6.588
virginica | 5.8 | 6.588
virginica | 7.1 | 6.588
...
平均长度因品种而异。借助
DISTINCT
，通过省略单个长度，你可以得到每个品种的平均长
度列表：
SELECT DISTINCT species,
avg(sepal_length_cm) OVER(PARTITION BY species) AS avgsepal
FROM memory.default.iris;
species | avgsepal
------------+----------
setosa | 5.006
virginica | 6.588
versicolor | 5.936
(3 rows)
Presto
中的窗函数支持所有的聚合函数以及许多窗特有的函数： ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.