Tips and methods for using HTML to read databases
为了使用 HTML 从数据库读取数据，有几种方法：使用 AJAX 调用，通过异步通信以无缝方式检索数据；使用 WebSockets，建立持久连接以实现实时数据传输；并且将响应格式化为 JSON，以便轻松客户端解析和处理。
利用 HTML 读取数据库：技巧与方法
简介
在 Web 应用程序中，从数据库读取数据是至关重要的任务。利用 HTML 作为客户端语言，我们可以轻松地与数据库交互并动态显示数据。本文介绍了几种有效的技巧和方法，帮助你有效地使用 HTML 读取数据库。
AJAX 调用
AJAX (Asynchronous JavaScript and XML) 允许你在不重新加载整个页面的情况下，与服务器进行异步通信。这使得从数据库读取数据变得高效且无缝。以下是使用 AJAX 调用读取数据的代码示例：
function getCustomers() {
var xhr = new XMLHttpRequest();
xhr.open("GET", "get_customers.php");
xhr.onload = function() {
if (xhr.status === 200) {
var customers = JSON.parse(xhr.responseText);
displayCustomers(customers);
} else {
alert("Error fetching customers.");
}
};
xhr.send();
}此函数通过 AJAX 调用向 get_customers.php 文件发送请求，后者从数据库检索客户数据。响应作为 JSON 格式返回，并在客户端解析和显示。
Web Sockets
Web Sockets 是另一种实现实时通信的强大技术。它允许客户端与服务器建立持久连接，从而可以持续读取数据库数据。以下是用 WebSocket 读取数据库数据的示例代码：
var websocket = new WebSocket("ws://localhost:8080");
websocket.onopen = function() {
websocket.send("get_customers");
};
websocket.onmessage = function(event) {
var data = JSON.parse(event.data);
if (data.type == "customers") {
displayCustomers(data.customers);
}
};此代码使用 WebSocket 对象连接到服务器，并发送一条消息以检索客户数据。服务器处理该请求并通过 WebSocket 连接持续发送数据。
使用 JSON 响应
无论使用 AJAX 还是 Web Sockets，使用 JSON 作为响应格式是一个明智的选择。JSON 是一种轻量级的文本格式，便于解析和处理客户端端。服务器端代码应将数据库数据转换为 JSON 对象，然后将其作为响应返回。
实战案例
任务：创建一个用户列表页面，该页面从数据库动态获取用户数据并显示。
步骤：
- 创建一个
get_users.php文件，该文件用于从数据库中获取用户数据并将其编码为 JSON：
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "myDB";
// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);
// 准备和执行查询
$sql = "SELECT * FROM users";
$result = $conn->query($sql);
// 将结果编码为 JSON
$users = array();
while ($row = $result->fetch_assoc()) {
$users[] = $row;
}
echo json_encode($users);
?>- 在 HTML 页面中使用 AJAX 调用检索用户数据并将其显示：
<script>
function getUsers() {
var xhr = new XMLHttpRequest();
xhr.open("GET", "get_users.php");
xhr.onload = function() {
if (xhr.status === 200) {
var users = JSON.parse(xhr.responseText);
displayUsers(users);
} else {
alert("Error fetching users.");
}
};
xhr.send();
}
</script>
<body onload="getUsers()">
<div id="user-list"></div>
</body>- 在 HTML 页面中创建
displayUsers()函数以显示用户数据。
通过遵循这些步骤，你将创建出利用 HTML 从数据库动态读取数据的用户列表页面。
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