3436. Find Valid Emails.sql

/*
Question 3436. Find Valid Emails
Link: https://leetcode.com/problems/find-valid-emails/description/?envType=problem-list-v2&envId=database

Table: Users

+-----------------+---------+
| Column Name     | Type    |
+-----------------+---------+
| user_id         | int     |
| email           | varchar |
+-----------------+---------+
(user_id) is the unique key for this table.
Each row contains a user's unique ID and email address.
Write a solution to find all the valid email addresses. A valid email address meets the following criteria:

It contains exactly one @ symbol.
It ends with .com.
The part before the @ symbol contains only alphanumeric characters and underscores.
The part after the @ symbol and before .com contains a domain name that contains only letters.
Return the result table ordered by user_id in ascending order.
*/

SELECT 
    user_id,
    email
FROM Users
WHERE email ~ '^([a-zA-Z0-9]?[_]?[a-zA-Z0-9]?)*@[a-zA-Z]+\.com$'
ORDER BY user_id ASC