PHP can't determine whether user is logged in or not - php

Question

I'm creating a system that the header will show 'login' if the user is not logged in, and if they are, it'll display logout. I've simplified it for now, just showing if the user is logged in or not. With "Login!" meaning they need to login, and "Welcome!" if they are logged in. I used the PHP Code Checker website (https://phpcodechecker.com/) and it couldn't find any errors. I also searched stackoverflow, and everyone else's seems to work.
<?php
ob_start();
session_start();
require_once 'dbconnect.php';
if( !isset($_SESSION['user']) ) {
echo "Login!";
} else {
echo "Welcome!";
}
?>
is the code that checks if the user is logged in or not.
My login page works for EVERYTHING else, for my homepage is shows that the user is logged in, but here is the code anyway. (This is only the PHP code, there is HTML for the submit button, ect.)
<?php
ob_start();
session_start();
require_once 'dbconnect.php';
// it will never let you open index(login) page if session is set
if ( isset($_SESSION['user'])!="" ) {
header("Location: index.php");
exit;
}
$error = false;
if( isset($_POST['btn-login']) ) {
// prevent sql injections/ clear user invalid inputs
$email = trim($_POST['email']);
$email = strip_tags($email);
$email = htmlspecialchars($email);
$name = trim($_POST['name']);
$name = strip_tags($name);
$name = htmlspecialchars($name);
$pass = trim($_POST['pass']);
$pass = strip_tags($pass);
$pass = htmlspecialchars($pass);
// prevent sql injections / clear user invalid inputs
if(empty($name)){
$error = true;
$nameError = "Please enter your username.";
}
if(empty($pass)){
$error = true;
$passError = "Please enter your password.";
}
// if there's no error, continue to login
if (!$error) {
$password = hash('sha256', $pass); // password hashing using SHA256
$res=mysql_query("SELECT userId, userEmail, userPass FROM users WHERE
userName='$name'");
$row=mysql_fetch_array($res);
$count = mysql_num_rows($res); // if email/pass correct it returns must be
1 row
if( $count == 1 && $row['userPass']==$password ) {
$_SESSION['user'] = $row['userId'];
header("Location: dashboard.php");
} else {
$errMSG = "Incorrect Credentials, Try again...";
}
}
}
?>
It connects to the database fine, and i'm certain there is no problems with the database, since it works on my other pages.
I've spent a long-while trying to figure this out, and can't.
Thanks!

Answer 1

In your code
if ( isset($_SESSION['user'])!="" ) {
you are comparing true|false != ""
change it to if (isset($_SESSION['user'])) {
or
if (isset($_SESSION['user']) && ($_SESSION['user']!="")) {