leetcode 1517 Find Users With Valid E-Mails [MYSQL]

리뷰

공부한 것

• RLIKE, REGEX 함수 - 문자열 패턴을 정규표현식을 사용해서 비교하고 일치 여부를 확인한다.

-- regular like, regular expression

RLIKE '^[조건 범위]'
REGEX '^[조건 범위]'

 

• 정규표현식 

a-zA-Z : 알파벳
0-9 : 숫자

^ : 문자열 시작 표시
[] : 범위 설정
+ : 조건 잇기
$ : 문자열 종료 설정. 설정하지 않으면 뒤에 문자열이 추가될 수 있다.
* : 직전의 조건 범위를 충족하는 문자의 개수는 0 이상이다.

\\. : 메타문자인 도트 앞에 이스케이프 문자(역슬래시) 두개 붙이기

 

문제

Table: Users

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| user_id       | int     |
| name          | varchar |
| mail          | varchar |
+---------------+---------+
user_id is the primary key (column with unique values) for this table.
This table contains information of the users signed up in a website. Some e-mails are invalid.

Write a solution to find the users who have valid emails.

A valid e-mail has a prefix name and a domain where:

• The prefix name is a string that may contain letters (upper or lower case), digits, underscore '_', period '.', and/or dash '-'. The prefix name must start with a letter.
• The domain is '@leetcode.com'.

Return the result table in any order.

The result format is in the following example.

Example 1:

Input:
Users table:
+---------+-----------+-------------------------+
| user_id | name      | mail                    |
+---------+-----------+-------------------------+
| 1       | Winston   | winston@leetcode.com    |
| 2       | Jonathan  | jonathanisgreat         |
| 3       | Annabelle | bella-@leetcode.com     |
| 4       | Sally     | sally.come@leetcode.com |
| 5       | Marwan    | quarz#2020@leetcode.com |
| 6       | David     | david69@gmail.com       |
| 7       | Shapiro   | .shapo@leetcode.com     |
+---------+-----------+-------------------------+
Output:
+---------+-----------+-------------------------+
| user_id | name      | mail                    |
+---------+-----------+-------------------------+
| 1       | Winston   | winston@leetcode.com    |
| 3       | Annabelle | bella-@leetcode.com     |
| 4       | Sally     | sally.come@leetcode.com |
+---------+-----------+-------------------------+
Explanation:
The mail of user 2 does not have a domain.
The mail of user 5 has the # sign which is not allowed.
The mail of user 6 does not have the leetcode domain.
The mail of user 7 starts with a period.

 

내 답안

select user_id, name, mail from Users 
where mail rlike '^[a-zA-Z][a-zA-Z0-9_.-]*+@leetcode\\.com$'