March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
158
｜
第
9
章
SELECT u&'\2168', 'IX', u&'\2168' = 'IX', normalize(u&'\2168', NFKC) = 'IX';
_col0 | _col1 | _col2 | _col3
-------+-------+-------+-------
Ⅸ | IX | false | true
(1 row)
9.13
正则表达式
Presto
通过提供
SQL
LIKE
运算符和正则表达式（
regex
）函数来支持模式匹配。
LIKE
返回
一个布尔值，语法为
搜索字段
LIKE
模式
。
LIKE
非常适用于只需要基本模式匹配的场合，但在其他场合可能表达力不足。
LIKE
模式支
持两个符号：
_
表示匹配任何一个字符，
%
表示匹配
0
个或多个字符。
假设你想找到从达拉斯地区出发的航班，可以写出下面的查询：
SELECT origincityname, count(*)
FROM flights_orc
WHERE origincityname LIKE '%Dallas%'
GROUP BY origincityname;
origincityname | _col1
-----------------------+---------
Dallas/Fort Worth, TX | 7601863
Dallas, TX | 1297795
(2 rows)
任何更复杂的模式匹配都需要使用正则表达式函数，这些函数使用
Java
模式语法提供的强
大模式匹配能力。表
9-10 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.