AJAX dapat digunakan untuk komunikasi interaktif dengan database.
Contoh Database AJAX
Contoh berikut akan menunjukkan bagaimana halaman web dapat mengambil informasi dari database dengan AJAX:
<!DOCTYPE html> <html> <style> table,th,td { border : 1px solid black; border-collapse: collapse; } th,td { padding: 5px; } </style> <body> <h1>The XMLHttpRequest Object</h1> <form action=""> <select name="customers" onchange="showCustomer(this.value)"> <option value="">Select a customer:</option> <option value="ALFKI">Alfreds Futterkiste</option> <option value="NORTS ">North/South</option> <option value="WOLZA">Wolski Zajazd</option> </select> </form> <br> <div id="txtHint">Customer info will be listed here...</div> <script> function showCustomer(str) { var xhttp; if (str == "") { document.getElementById("txtHint").innerHTML = ""; return; } xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { document.getElementById("txtHint").innerHTML = this.responseText; } }; xhttp.open("GET", "getcustomer.asp?q="+str, true); xhttp.send(); } </script> </body> </html>
Penjelasan Contoh – Fungsi showCustomer ()
Saat pengguna memilih pelanggan dalam daftar tarik-turun di atas, fungsi yang disebut “showCustomer ()” dijalankan. Fungsi ini dipicu oleh peristiwa “onchange”:
showCustomer
function showCustomer(str) {
var xhttp;
if (str == "") {
document.getElementById("txtHint").innerHTML = "";
return;
}
xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("txtHint").innerHTML = this.responseText;
}
};
xhttp.open("GET", "getcustomer.php?q="+str, true);
xhttp.send();
}Fungsi showCustomer () melakukan hal berikut:
- Periksa apakah pelanggan dipilih
- Buat objek XMLHttpRequest
- Buat fungsi untuk dijalankan saat respons server siap
- Kirim permintaan ke file di server
- Perhatikan bahwa parameter (q) ditambahkan ke URL (dengan konten daftar dropdown)
Halaman Server AJAX
Halaman di server yang disebut dengan JavaScript di atas adalah file PHP yang disebut “getcustomer.php”.
Kode sumber di “getcustomer.php” menjalankan kueri terhadap database, dan mengembalikan hasilnya dalam tabel HTML:
<?php
$mysqli = new mysqli("servername", "username", "password", "dbname");
if($mysqli->connect_error) {
exit('Could not connect');
}
$sql = "SELECT customerid, companyname, contactname, address, city, postalcode, country
FROM customers WHERE customerid = ?";
$stmt = $mysqli->prepare($sql);
$stmt->bind_param("s", $_GET['q']);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($cid, $cname, $name, $adr, $city, $pcode, $country);
$stmt->fetch();
$stmt->close();
echo "<table>";
echo "<tr>";
echo "<th>CustomerID</th>";
echo "<td>" . $cid . "</td>";
echo "<th>CompanyName</th>";
echo "<td>" . $cname . "</td>";
echo "<th>ContactName</th>";
echo "<td>" . $name . "</td>";
echo "<th>Address</th>";
echo "<td>" . $adr . "</td>";
echo "<th>City</th>";
echo "<td>" . $city . "</td>";
echo "<th>PostalCode</th>";
echo "<td>" . $pcode . "</td>";
echo "<th>Country</th>";
echo "<td>" . $country . "</td>";
echo "</tr>";
echo "</table>";
?>