id          Primaria     int(11)
username                 varchar(50)
name                     varchar(50)
email                    varchar(100)
password                 varchar(60)

$query = mysqli_query($con,"SELECT * FROM user WHERE email ="$email" OR username="$email" AND password = "$password";");

$query = mysqli_query($con,"SELECT * FROM user WHERE (email ="$email" OR username="$email") AND password = "$password";");