7-Modern-Languages-in-7-Weeks---Systems--Security---Algorithms-Track/week 1/day3/exo3.sql

-- exo 3

SELECT username,
       CASE
           WHEN length(username) <= 20
                AND username ~ '^[A-Za-z]+$'
           THEN 'Accepted'
           ELSE 'Refused'
       END AS status
FROM users;