php访问数据库实例

<?php
try {
    // 创建 PDO 实例
    $dsn = 'mysql:host=localhost;dbname=testdb;charset=utf8';
    $username = 'root';
    $password = 'password';
    $pdo = new PDO($dsn, $username, $password);

    // 设置错误模式
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 执行查询
    $stmt = $pdo->query('SELECT * FROM users');
    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo 'ID: ' . $row['id'] . ', Name: ' . $row['name'] . '<br>';
    }
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}
?>

<?php
try {
    $dsn = 'mysql:host=localhost;dbname=testdb;charset=utf8';
    $username = 'root';
    $password = 'password';
    $pdo = new PDO($dsn, $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 使用预处理语句
    $stmt = $pdo->prepare('SELECT * FROM users WHERE id = :id');
    $stmt->bindParam(':id', $userId, PDO::PARAM_INT);
    $userId = 1;
    $stmt->execute();

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo 'ID: ' . $row['id'] . ', Name: ' . $row['name'] . '<br>';
    }
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}
?>