How To Upload Image Into Database

<?php

    require_once("connection.php");

    if($_SERVER["REQUEST_METHOD"] == "POST"){

        $userName = $_POST["username"];

        $avatar = $_FILES["avatar"];

        $avatarName = $_FILES["avatar"]["name"];
        $avatarType = $_FILES["avatar"]["type"];
        $avatarTmp = $_FILES["avatar"]["tmp_name"];
        $avatarSize = $_FILES["avatar"]["size"];

        if(!empty($avatarTmp)){

            if($avatarSize < 4194303){ // 4194303 = 4mb

                $avatarExtensionList = array("jpeg","jpg","png","gif");
                $avatarExtension = strtolower(end(explode(".",$avatarName)));

                if(in_array($avatarExtension,$avatarExtensionList)){

                    move_uploaded_file($avatarTmp,"image\\" . $avatarName);
                    // "image\\" directory where you will put images uploaded

                    $sql = "INSERT INTO upload(username,avatar)
                    VALUES(:username,:avatar)";

                    $stmt = $connect->prepare($sql);

                    // bind value to a paramater

                    $stmt->bindValue(":username",$userName,PDO::PARAM_STR);
                    $stmt->bindValue(":avatar",$avatarName,PDO::PARAM_STR);

                    $stmt->execute();

                    $msg = "New Record Add To Database";

                }else{

                    $msg = "Unvalid Type Image";

                }
            }else{

                $msg = "Unvalid Size Image";

            }

        }else{

            $msg = "Empty Field Image";

        }

    }
// close connection

$connect = NULL;
?>
<?php  require_once("head.html"); ?>

<div class="container">
    <center><h3>CodeJs : How To Upload Image Into Database </h3></center><br /><br />

        <form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>" method="POST" enctype="multipart/form-data">

            <div class="form-group"> <!-- input text -->
                <label for="username">Username :</label>

                <input type="text" class="form-control" placeholder="Your Username" name="username">
            </div>

            <div class="form-group"> <!-- input text -->
                <label for="username">Avatar :</label>

                <input type="file" class="form-control" name="avatar">
                <br />
            </div>

            <button type="submit" class="btn btn-primary">Register</button> <!-- button submit -->

            <br /><br />


                <div class="alert alert-danger">
                    <?php if(isset($msg)){ echo $msg; } ?>
                </div>  <!-- Alert Message -->

        </form>
                <img src=""> <!-- Image -->
</div>


<style>
img{ width:100px; height: 100px; background: gainsboro; }
form, h2{ width: 400px; margin: 0 auto; }
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>
</html>