如何使用 PHP 函数来操作数据库

<?php
$servername = "localhost";
$username = "root";
$password = "password";
$dbname = "mydb";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("连接失败：" . $conn->connect_error);
}
?>

<?php
// 预备查询
$stmt = $conn->prepare("SELECT * FROM customers WHERE name = ?");

// 绑定参数
$stmt->bind_param("s", $name);

// 设置参数
$name = "John Doe";

// 执行查询
$stmt->execute();

// 绑定结果
$stmt->bind_result($id, $name, $email);

// 循环结果
while ($stmt->fetch()) {
    echo "ID: $id, 姓名: $name, 邮箱: $email<br>";
}

// 关闭语句
$stmt->close();
?>

<?php
// 预备查询
$stmt = $conn->prepare("INSERT INTO customers (name, email) VALUES (?, ?)");

// 绑定参数
$stmt->bind_param("ss", $name, $email);

// 设置参数
$name = "Jane Doe";
$email = "jane.doe@example.com";

// 执行查询
$stmt->execute();

// 获取自增 ID（如果有）
$id = $conn->insert_id;

// 关闭语句
$stmt->close();

echo "新记录已插入，ID 为：$id";
?>

<?php
// 预备查询
$stmt = $conn->prepare("UPDATE customers SET name = ? WHERE id = ?");

// 绑定参数
$stmt->bind_param("si", $name, $id);

// 设置参数
$name = "John Smith";
$id = 1;

// 执行查询
$stmt->execute();

// 关闭语句
$stmt->close();

echo "记录已更新";
?>

<?php
// 预备查询
$stmt = $conn->prepare("DELETE FROM customers WHERE id = ?");

// 绑定参数
$stmt->bind_param("i", $id);

// 设置参数
$id = 1;

// 执行查询
$stmt->execute();

// 关闭语句
$stmt->close();

echo "记录已删除";
?>

<?php
// 关闭连接
$conn->close();
?>

<?php
// 连接数据库
...

// 查询博客文章
$stmt = $conn->prepare("SELECT * FROM blog_posts ORDER BY created_at DESC");
$stmt->execute();
$stmt->bind_result($id, $title, $content, $created_at);

// 循环结果，显示博客文章
while ($stmt->fetch()) {
    echo "<h1>$title</h1>";
    echo "<p>$content</p>";
    echo "<p>Created: $created_at</p>";
    echo "<hr>";
}

// 关闭语句
$stmt->close();
?>