php的update语句怎么写

<?php
// 数据库连接配置
$host = 'localhost';
$dbname = 'your_database';
$user = 'your_username';
$pass = 'your_password';

try {
    // 创建PDO实例
    $pdo = new PDO("mysql:host=$host;dbname=$dbname;charset=utf8", $user, $pass);

    // 构建UPDATE语句
    $table = 'your_table';
    $data = [
        'column1' => 'new_value1',
        'column2' => 'new_value2'
    ];
    $where = 'id = 1'; // 更新条件

    $set = '';
    foreach ($data as $column => $value) {
        $set .= "`$column` = :$column, ";
    }
    $set = rtrim($set, ', '); // 去掉最后一个逗号和空格

    $sql = "UPDATE `$table` SET $set WHERE $where";

    // 准备并绑定参数
    $stmt = $pdo->prepare($sql);
    foreach ($data as $column => $value) {
        $stmt->bindValue(":$column", $value);
    }

    // 执行SQL语句
    $stmt->execute();

    // 处理结果
    if ($stmt->rowCount() > 0) {
        echo "记录更新成功";
    } else {
        echo "没有记录被更新";
    }
} catch (PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}
?>