php查询mysql表的行数据

<?php
try {
    // 连接数据库
    $pdo = new PDO('mysql:host=localhost;dbname=testdb', 'username', 'password');

    // 查询表数据
    $stmt = $pdo->query('SELECT * FROM users');

    // 遍历结果集
    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 {
    $pdo = new PDO('mysql:host=localhost;dbname=testdb', 'username', 'password');

    $stmt = $pdo->prepare('SELECT * FROM users WHERE id = :id');
    $stmt->bindParam(':id', $id, PDO::PARAM_INT);

    $id = 1; // 假设这是用户输入
    $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();
}
?>