PHP 数据库操作示例

本教程提供 PHP 连接数据库、写入、插入、读取和修改数据的示例，使用单独的 config.php 文件存储数据库配置信息。

1. 连接数据库

```php $conn = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);

if (!$conn) { die('连接数据库失败: ' . mysqli_connect_error()); } echo '连接数据库成功'; ?>

<h2>2. 写入数据库</h2>
```php
<?php
require_once 'config.php';

$conn = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);

if (!$conn) {
    die('连接数据库失败: ' . mysqli_connect_error());
}

$sql = 'INSERT INTO users (name, email) VALUES ('John Doe', 'john@example.com')';

if (mysqli_query($conn, $sql)) {
    echo '新纪录插入成功';
} else {
    echo 'Error: ' . $sql . '<br>' . mysqli_error($conn);
}

mysqli_close($conn);
?>

3. 插入数据库

```php $conn = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);

if (!$conn) { die('连接数据库失败: ' . mysqli_connect_error()); }

$sql = 'SELECT * FROM users'; $result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) { while ($row = mysqli_fetch_assoc($result)) { echo 'ID: ' . $row['id'] . ' - Name: ' . $row['name'] . ' - Email: ' . $row['email'] . '
'; } } else { echo '0 结果'; }

mysqli_close($conn); ?>

<h2>4. 修改数据库</h2>
```php
<?php
require_once 'config.php';

$conn = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);

if (!$conn) {
    die('连接数据库失败: ' . mysqli_connect_error());
}

$sql = 'UPDATE users SET email='john.doe@example.com' WHERE id=1';

if (mysqli_query($conn, $sql)) {
    echo '记录更新成功';
} else {
    echo 'Error updating record: ' . mysqli_error($conn);
}

mysqli_close($conn);
?>