[SQL 문제 풀이] Find Users With Valid E-Mails (유효한 이메일을 사용하는 사용자 찾기)

Can you solve this real interview question? Find Users With Valid E-Mails - 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.