July 2023
Intermediate to advanced
278 pages
5h 40m
Chinese
Content preview from Trino 权威指南：原书第2版
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高级
SQL
特性
|
183
关重要，在这些应用程序中，你可能经常要转换、比较或提取时间元素。表
9-14
展示了
一些可用的函数。请查看
1.4.2
节了解更多有用的函数和其他技巧。
表 9-14：一些时态函数和值
函数 返回类型 描述
current_timezone() VARCHAR 返回当前时区
current_date DATE 返回当前日期
current_time TIME WITH TIME ZONE 返回当前日期和时区
current_timestamp or now() TIMESTAMP WITH
TIME ZONE
返回当前时间
、
日期和时区
localtime TIME 基于本地时区返回当前时间
localtimestamp TIMESTAMP 基于本地时区返回当前的日期
和时间
from_unixtime(unixtime) TIMESTAMP 将一个 UNIX 时间转换为日期
和时间
to_unixtime(timestamp) DOUBLE 将日期和时间转换为 UNIX 时
间值
to_milliseconds(interval) BIGINT 将时间间隔转换为毫秒
9.17
直方图
Trino
提供了
width_bucket
函数用来创建等宽直方图：
width_bucket(x, bound1, bound2, n) -> bigint
表达式
x
表示用来创建直方图的数值。等宽直方图包含
n
个桶，并使用
bound1
和
bound2
作为值的界限。该函数返回表达式
x
的每个值对应的桶编号。
让我们以航班数据集为例，计算出从 ...
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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.