GET User ID to show catergories - php

Question

I am trying to show only categories a user can see by assigning a the category ID inside of the user table.
I am logging in using the following script:
login.php
<?
session_start();
if(isset($_SESSION['user'])){
header("Location:home.php");
exit;
}
$dbh=new PDO('mysql:dbname=dashboardr;host=######', '######', '######');
$email=$_POST['username'];
$password=$_POST['pass'];
if(isset($_POST) && $email!='' && $password!=''){
$sql=$dbh->prepare("SELECT * FROM user_login WHERE username=?");
$sql->execute(array($email));
while($r=$sql->fetch()){
$p=$r['password'];
$p_salt=$r['psalt'];
$id=$r['id'];
$email=$r['username'];
$firstname=$r['firstname'];
$lastname=$r['lastname'];
}
$site_salt="subinsblogsalt";
$salted_hash = hash('sha256',$password.$site_salt.$p_salt);
if($p==$salted_hash){
$_SESSION['user']=$id;
$_SESSION['username']=$email;
$_SESSION['firstname']=$firstname;
$_SESSION['lastname']=$lastname;
header("Location:home.php");
}else{
echo "<h2>Username/Password is Incorrect.</h2>";
}
}
?>
Inside of the home.php file where it shows you are logged in here is where I need to show the categories which are inside of the 'cat_no' column which lised inside of the 'user_login' table.
Here is where I am wanting to GET the users ID and display those categories.
home.php
<?php require_once '../db_con.php';
if(!empty($_GET['user_id'])){
$cat = intval($_GET['user_id']);
try{
$results = $dbh->prepare("SELECT * FROM user_login WHERE FIND_IN_SET(?, cat_no)");
$results->bindParam(1, $cat);
$results->execute();
var_dump($cat);
} catch(Exception $e) {
echo $e->getMessage();
die();
}
$doc = $results->fetchAll(PDO::FETCH_ASSOC);
if($doc == FALSE){
echo '<div class="container">';
echo "<img src='../img/404.jpg' style='margin: 40px auto; display: block;' />";
echo "<h1 style='margin: 40px auto; display: block; text-align: center;' />Oh Crumbs! You upset the bubba!</h1>";
echo 'Get me outta here!';
echo'</div>';
die();
}
}
?>
My tables look like the following:
CREATE TABLE `cat_list` (
`cat_id` int(11) NOT NULL,
`cat_title` varchar(32) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf16 AUTO_INCREMENT=5 ;
CREATE TABLE `user_login` (
`id` int(11) NOT NULL,
`username` text NOT NULL,
`firstname` varchar(30) NOT NULL,
`lastname` varchar(50) NOT NULL,
`password` varchar(64) NOT NULL,
`psalt` text NOT NULL,
`col_no` text NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=12 ;
I am confused on how to GET the logged in users Id and show the categories which are listed out inside of the col_no column in the user_login table.