php 关闭mysql连接

<?php
$mysqli = new mysqli("localhost", "user", "password", "database");

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

// 执行数据库操作
$result = $mysqli->query("SELECT * FROM table");

// 处理查询结果
while ($row = $result->fetch_assoc()) {
    // 处理每一行数据
}

// 关闭连接
$mysqli->close();
?>

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=database", "user", "password");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 执行数据库操作
    $stmt = $pdo->query("SELECT * FROM table");
    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        // 处理每一行数据
    }
} catch (PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
} finally {
    // 关闭连接
    $pdo = null;
}
?>