Banned account in SQL not working - php

Question

Why can't i block users with banstatus "Banned" from accessing the website? The error now is that the php banned all users from accessing the website even when their banstatus is not banned. Please help to identify the error as i have been trying to solve the error for a long time and couldn't solve it still. Thank you in advance :)
These are my codes:
if(!empty($_POST['username'])){
$username=$_POST['username'];
}
else
{
$username=null;
echo "<font color='red'> Please enter your username! </font></p>";
}
if(!empty($_POST['password'])){
$password= md5($_POST['password']);
}
else
{
$password=null;
echo "<font color='red'> Please enter your password! </font></p>";
}
if ($username && $password) {
$connection = mysql_connect("", "", "", "");
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysql_real_escape_string($username);
$password = mysql_real_escape_string($password);
$db = mysql_select_db("", $connection);
$query = mysql_query("SELECT * FROM users WHERE username='$username' and password='$password' and active=1", $connection);
$rows = mysql_num_rows($query);
if ($rows == 1) {
if ($rows['banstatus'] == '') {
session_start();
$_SESSION['username'] = $username;
header("Location:somewhere.php");
}
else{
echo "<br><br><br><b><font color='red'>Your account has been banned. Please contact the administrator.</font></b><br><br>";
}
}
else {
echo "<br><br><br><b><font color='red'> Login is not successful.</font></b><br><br>";
}
mysql_close($connection); // Closing Connection
}

Answer 1

if(!empty($_POST['username'])){
$username=$_POST['username'];
}
else
{
$username=null;
echo "<font color='red'> Please enter your username! </font></p>";
}
if(!empty($_POST['password'])){
$password= md5($_POST['password']);
}
else
{
$password=null;
echo "<font color='red'> Please enter your password! </font></p>";
}
if ($username && $password) {
$connection = new mysqli($your_db_IP_ADDR, $your_db_username, $your_db_pass, $your_db_database_name);
/*$username = stripslashes($username);*/ //if you using mysqli real_escape_string you don't need to stripslashes
/*$password = stripslashes($password);*/ //MD5 is an hash. You don't need to stripslashes it
$username = $connection->real_escape_string($username);
/*$password = $connection->real_escape_string($password)*/ // your $password is an MD5 hash. You don't need to escape it;
$results = $connection->query("SELECT * FROM users WHERE username='$username' and password='$password' and active = 1");
if ($results->num_rows === 1) {
$row = $results->fetch_assoc(); //call it row, it just one
if ($row['banstatus'] === '') {
session_start();
$_SESSION['username'] = $username;
$connection->close(); // Closing Connection also HERE before redirect
header("Location:somewhere.php");
} else {
echo "<br><br><br><b><font color='red'>Your account has been banned. Please contact the administrator.</font></b><br><br>";
}
} else {
echo "<br><br><br><b><font color='red'> Login is not successful.</font></b><br><br>";
}
$mysqli->close();
}