Login with user or email in the same field [duplicate]

In order to be able to log in with username and email at the same time, you must add query an OR. Example

SELECT username, password FROM users 
WHERE (username = "usernameRecebido" OR email = "emailRecebido") 
AND password = "passwordRecebido"

If I understood your question and your code, you just put a OR :

$userq = mysql_query("SELECT username, password FROM users WHERE (username = '{HoloText($_POST['credentials_username'])}' OR mail='$email') AND password = '$pwd' LIMIT 1");

Tip: Sometimes using javascript to do a field validation gets better and simpler.