php实现mysql

PHP 连接 MySQL 数据库

PHP 与 MySQL 数据库交互通常使用 mysqli 或 PDO 扩展。以下是两种方法的实现示例。

使用 mysqli 扩展

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

// 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);
}
echo "连接成功";
?>

使用 PDO 扩展

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

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // 设置 PDO 错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "连接成功"; 
}
catch(PDOException $e) {
    echo "连接失败: " . $e->getMessage();
}
?>

执行 SQL 查询

使用 mysqli 查询数据

$sql = "SELECT id, name, email FROM users";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出数据
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";
    }
} else {
    echo "0 结果";
}

使用 PDO 查询数据

$stmt = $conn->prepare("SELECT id, name, email FROM users");
$stmt->execute();

// 设置结果集为关联数组
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
foreach($stmt->fetchAll() as $row) {
    echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";
}

插入数据

使用 mysqli 插入数据

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

if ($conn->query($sql) === TRUE) {
    echo "新记录插入成功";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

使用 PDO 插入数据

$stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");
$stmt->bindParam(':name', $name);
$stmt->bindParam(':email', $email);

// 插入一行
$name = "John Doe";
$email = "john@example.com";
$stmt->execute();

echo "新记录插入成功";

关闭连接

mysqli 关闭连接

$conn->close();

PDO 关闭连接

$conn = null;

预处理语句防止 SQL 注入

使用预处理语句是防止 SQL 注入的最佳实践。

mysqli 预处理语句

$stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);

$name = "John Doe";
$email = "john@example.com";
$stmt->execute();

echo "新记录插入成功";
$stmt->close();

PDO 预处理语句

$stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");
$stmt->bindParam(':name', $name);
$stmt->bindParam(':email', $email);

$name = "John Doe";
$email = "john@example.com";
$stmt->execute();

echo "新记录插入成功";

错误处理

mysqli 错误处理

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

if ($conn->query($sql) === FALSE) {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

PDO 错误处理

try {
    // 数据库操作
} catch(PDOException $e) {
    echo "错误: " . $e->getMessage();
}

以上代码示例展示了 PHP 与 MySQL 数据库的基本交互方式，包括连接、查询、插入数据和关闭连接等操作。