mysqli_query insert help!!

<?php
    $servername = "localhost";
    $username = "<Username Name here>";
    $password = "<Password here>";
    $dbname = "<Database Name here>";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }
    
    if(isset($_GET['e'])){
        $value = mysqli_real_escape_string($conn, $_GET['e']);
    }
    //echo $value;
    //$url = parse_url ($_SERVER['HTTP_REFERER']);
        
    $sql = "INSERT INTO hitlog(hostname, ip, os, browser, city, referer, email, date) VALUES ('".$hostname."', '".$_SERVER['REMOTE_ADDR']."', '".$os."', '".$browser."', '".whois_info()."', '".$_SERVER['HTTP_REFERER']."', ".$_GET['email']."', ".$value."', NOW())";

    if (mysqli_query($conn, $sql)) {
        echo "Done!";
    } else {
        echo "Error: " . $sql . "" . mysqli_error($conn);
    }
    $conn->close();
?>