PHP数据库错误处理 PHP操作MySQL异常捕获教程

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

if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}

$sql = "SELECT * FROM users";
$result = $mysqli->query($sql);

if (!$result) {
    echo "Error: " . $mysqli->error;
} else {
    // 处理结果集
    while($row = $result->fetch_assoc()) {
        echo "ID: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
}

$mysqli->close();
?>

<?php
try {
    $pdo = new PDO("mysql:host=localhost;dbname=database", "user", "password");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); // 设置PDO错误模式为抛出异常

    $sql = "SELECT * FROM users WHERE id = ?";
    $stmt = $pdo->prepare($sql);
    $stmt->execute([1]); // 假设查询ID为1的用户

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo "ID: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }

} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
    // 可以记录错误日志，方便调试
    error_log("Database error: " . $e->getMessage());
} finally {
    // 可选：关闭连接，释放资源
    $pdo = null;
}
?>

<?php
function customErrorHandler($errno, $errstr, $errfile, $errline) {
    $logMessage = "Error: [$errno] $errstr - $errfile:$errline" . PHP_EOL;
    error_log($logMessage, 3, "/path/to/error.log"); // 写入日志文件
    // 发送邮件通知管理员（可选）
    // mail("admin@example.com", "PHP Error", $logMessage);
}

set_error_handler("customErrorHandler");

// 触发一个错误
$undefinedVariable++;
?>

<?php
// 使用PDO预处理语句
$pdo = new PDO("mysql:host=localhost;dbname=database", "user", "password");
$sql = "SELECT * FROM users WHERE username = :username AND password = :password";
$stmt = $pdo->prepare($sql);
$stmt->execute(['username' => $_POST['username'], 'password' => $_POST['password']]);

// 或者使用MySQLi的预处理语句
$mysqli = new mysqli("localhost", "user", "password", "database");
$stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $_POST['username'], $_POST['password']);
$stmt->execute();
?>