Seleccione Duplicados en SQL
SELECT username, email, COUNT(*)
FROM users
GROUP BY username, email
HAVING COUNT(*) > 1
Cucumberman
SELECT username, email, COUNT(*)
FROM users
GROUP BY username, email
HAVING COUNT(*) > 1
/* This SQL Query will show each of those duplicate
rows individually instead of just grouping it */
SELECT username,email
FROM `users`
WHERE `username`
IN (SELECT username FROM `users` GROUP BY username HAVING COUNT(username) > 1)