Display specific data from sql database : I have a database called 'members' with a table called 'users'. The users table has an 'id' column that auto-increments every time a new user is added. I want to fetch the id of the logged in user and display that singular row of data.
This is my login code:

        <?php
        session_start();
        // Connect to server and select databse.
        mysql_connect("localhost", "root", "")or die("cannot connect"); 
        mysql_select_db("members")or die("cannot select DB");
        // username and password sent from form 
        $prepreemail=$_POST['email']; 
        $prepremypassword=$_POST['mypassword']; 
        $preemail = stripslashes($prepreemail);
        $premypassword = stripslashes($prepremypassword);
        $email = mysql_real_escape_string($preemail);
        $mypassword = mysql_real_escape_string($premypassword);
        $sql="SELECT * FROM users WHERE email='$email' and password='$mypassword'";
        $result=mysql_query($sql);


        // Mysql_num_row is counting table row
        $count=mysql_num_rows($result);
        // If result matched $myusername and $mypassword, table row must be 1 row
        if($count==1){
        // Register $myusername, $mypassword and redirect to file "login_success.php"
        header ("location:home.html");
        }
        else 
        {
        header ("location:sign_in.php");
        }
        ?>

This is my sign up code

        <?php
        session_start();
        $con = mysql_connect("localhost","root","");
        if (!$con)
          {
          die('Could not connect: ' . mysql_error());
          }
 
        mysql_select_db("members", $con);
 
        $sql="INSERT INTO users (name, email, address, dob, password)
        VALUES
        ('$_POST[name]','$_POST[email]','$_POST[address]','$_POST[dob]','$_POST[mypassword]')";
 
        if (!mysql_query($sql,$con)) die('Error: ' . mysql_error());
        $_SESSION['userID'] = "SELECT id from users";

        {
	        header ("Location: sign_in.php");
	        exit;
        }
 
        mysql_close($con)
        ?>

And this is my display user details code:

        <?php
        session_start();
        // Create connection
        $conn = new mysqli("localhost", "root", "", "members");
        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        } 
        $userID = $_SESSION['userID'];
        $sql = "SELECT name, email, address, dob FROM users WHERE `users`.`id`=$userID";
        $result = $conn->query($sql);

        if ($result->num_rows > 0) {
            echo "<table><tr><th>Name</th><th>Email</th><th>Address</th><th>DOB</th></tr>";
            // output data of each row
            while($row = $result->fetch_assoc()) {
                echo "<tr><td>".$row["name"]."</td><td>".$row["email"]."</td><td>".$row["address"]."</td><td>".$row["dob"]."</td></tr>";
            }
            echo "</table>";
        } else {
                echo "<p>No Details</p><style>p{color: #336699; font-size: 20pt; font-family: Gulim; font-weight: bold; align: center; padding: 10px; position: absolute; top: 250; left: 600; z-index: 2; border-spacing: 0px;}</style> ";
        }
        $conn->close();
        ?>

For some reason it is not working, someone please help!