Mysql query always returning true

Question

So I am trying to check if a user is banned using a mysqli query however it always seems to return that the user is banned. Even though they are not banned.

user_banned function

function user_banned ($con, $username) {
    $data = $username;
    $username = sanitize($data, $con); 
    $username = $data;
    mysqli_query($con, "SELECT `banned` FROM `users` WHERE `username` = '$username'");
    return(mysqli_affected_rows($con) == 1) ? true : false;
}

Place where I call the function:

$username = $_POST['username'];
$password = $_POST['password'];

if (user_banned($con, $username) === true ) {
    $errors[] = 'You are banned, contact an admin.';
}

I have echo'd the $username and it is the correct username, so that is not the issue.

TL;dr function always returns true for some reason.

Answer 1

mysqli_affected_rows() is for INSERT and UPDATE. You want mysqli_num_rows() .

Your current logic would return false if there happen to be more than 1 rows so this might make more sense:

return(mysqli_affected_rows($con) != 0) ? true : false;
//or even
return (bool)mysqli_affected_rows($con);

Also, what the **** is this? It does absolutely nothing.

$data = $username;
$username = sanitize($data, $con); 
$username = $data;

Answer 2

Your not checking the value of banned your just selecting a row and returning true if it exists. You need to either add a where clause to check the value of banned or inspect it in php and decide if the user is banned or not