new user management system using ajax

sys0-code/api/update_user.php

@@ -0,0 +1,34 @@
+<?php
+session_start();
+if (!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true || $_SESSION["role"][3] !== "1") {
+    header("location: /login/login.php");
+    exit;
+}
+require_once "../config/config.php";
+
+$userId = $_POST['userId'];
+$field = $_POST['field'];
+$value = $_POST['value'];
+
+if (strpos($field, 'role') !== false) {
+    $index = (int)filter_var($field, FILTER_SANITIZE_NUMBER_INT);
+    $sql = "SELECT role FROM users WHERE id = ?";
+    $stmt = $link->prepare($sql);
+    $stmt->bind_param("i", $userId);
+    $stmt->execute();
+    $stmt->bind_result($role);
+    $stmt->fetch();
+    $stmt->close();
+
+    $role[$index] = $value;
+    $sql = "UPDATE users SET role = ? WHERE id = ?";
+    $stmt = $link->prepare($sql);
+    $stmt->bind_param("si", $role, $userId);
+} else {
+    $sql = "UPDATE users SET $field = ? WHERE id = ?";
+    $stmt = $link->prepare($sql);
+    $stmt->bind_param("ii", $value, $userId);
+}
+$stmt->execute();
+$stmt->close();
+?>