1517. Find Users With Valid E-Mails

Pandas

import pandas as pd


def valid_emails(users: pd.DataFrame) -> pd.DataFrame:
    return users[users['mail'].str.match(r'^[a-zA-Z][a-zA-Z0-9_.-]*@leetcode\.com$')]

SQL

SELECT
    user_id,
    name,
    mail
FROM Users
WHERE mail REGEXP '^[a-zA-Z][a-zA-Z0-9_.-]*@leetcode\\.com$'