DEFINE('DB_USER','root');
DEFINE('DB_PSWRD','root');
DEFINE('DB_HOST','localhost');
DEFINE('DB_NAME','mydatabase');

$dbcon = mysqli_connect(DB_HOST,DB_USER,DB_PSWRD,DB_NAME);

if(!$dbcon){
  die('error connecting to database');
}

echo 'connected to database'; // displays this message

$sql = mysql_query("SELECT * FROM users where id='1'");
$sqla = mysql_fetch_array($sql);
do {
  print $sqla['username']; // displays nothing
}
while($sqla = mysql_fetch_array($sql));