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
｜
151
WHERE year > 2010 AND year < 2014
GROUP BY carrier, year;
avg_arrival_delay | carrier
--------------------+---------
11.755326255888736 | 9E
12.557365851045104 | AA
13.39056266711295 | AA
13.302276406082575 | AA
6.4657695873247745 | AS
7.048865559750841 | AS
6.907012760530203 | AS
17.008730526574663 | B6
13.28933909176506 | B6
16.242635221309246 | B6
...
9.4
逻辑运算符
在
SQL
和
Presto
中还有三个
逻辑运算符
：
AND
、
OR
和
NOT
。运算符
AND
和
OR
是
双目运算符
，
因为它们接受两个参数作为输入。
NOT
是一个单目运算符，它只接受一个参数作为输入。
这些逻辑运算符接收
BOOLEAN
类型的输入数据，返回单个布尔变量
TRUE
、
FALSE
或
NULL
（
UNKNOWN
）。通常，这些运算符组合使用形成条件子句，就像布尔运算符那样。
这三个运算符的概念与编程语言相似，但由于
NULL
值的存在，语义有所不同。例如，
NULL
AND NULL
不等于
TRUE
，而是等于
NULL
。如果你把
NULL
看作值的缺失，这就很容易理解了。 ...
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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.