php – Overwrite files once the database reaches a specified number of posts

Question

Hello I am making a system in php in which there can only be a limited number of images in the database and when someone uploads new photos, the old ones will be deleted from the database. I currently have this:

<?php

if (isset($_POST['submit']) && isset($_FILES['my_image'])) {
include "db_conn.php";

echo "<pre>";
print_r($_FILES['my_image']); echo "</pre>";$img_name = $_FILES['my_image']['name'];$img_size = $_FILES['my_image']['size'];$tmp_name = $_FILES['my_image']['tmp_name'];$error = $_FILES['my_image']['error']; if ($error === 0) {
if ($img_size > 125000) {$em = "Sorry, your file is too large.";
header("Location: index.php?error=$em"); }else {$img_ex = pathinfo($img_name, PATHINFO_EXTENSION);$img_ex_lc = strtolower($img_ex);$allowed_exs = array("jpg", "jpeg", "png");

if (in_array($img_ex_lc,$allowed_exs)) {
$new_img_name = uniqid("IMG-", true).'.'.$img_ex_lc;
$img_upload_path="uploads/".$new_img_name;
move_uploaded_file($tmp_name,$img_upload_path);

// Insert into Database
$sql = "INSERT INTO images(image_url) VALUES('$new_img_name')";
mysqli_query($conn,$sql);
}else {
$em = "You can't upload files of this type"; header("Location: index.php?error=$em");
}
}
}else {
$em = "unknown error occurred!"; header("Location: index.php?error=$em");
}

}else {