php数据库如何使用事务 php数据库银行转账操作的实例

<?php
$host = 'localhost';
$db   = 'test_db';
$user = 'root';
$pass = '';
$charset = 'utf8mb4';
<p>$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::ATTR_EMULATE_PREPARES   => false,
];</p><p>try {
$pdo = new PDO($dsn, $user, $pass, $options);</p><pre class='brush:php;toolbar:false;'>// 开始事务
$pdo->beginTransaction();

// 转出账户减钱（例如：用户A转出100元）
$sql1 = "UPDATE accounts SET balance = balance - 100 WHERE id = 1";
$stmt1 = $pdo->prepare($sql1);
$stmt1->execute();

// 检查是否更新成功
if ($stmt1->rowCount() == 0) {
    throw new Exception("转出账户操作失败，账户可能不存在");
}

// 转入账户加钱（用户B收到100元）
$sql2 = "UPDATE accounts SET balance = balance + 100 WHERE id = 2";
$stmt2 = $pdo->prepare($sql2);
$stmt2->execute();

if ($stmt2->rowCount() == 0) {
    throw new Exception("转入账户操作失败，账户可能不存在");
}

// 检查转入账户余额是否正常（可选校验）
$checkSql = "SELECT balance FROM accounts WHERE id = 2";
$checkStmt = $pdo->query($checkSql);
$result = $checkStmt->fetch();
if ($result['balance'] < 0) {
    throw new Exception("目标账户余额异常");
}

// 所有操作成功，提交事务
$pdo->commit();
echo "转账成功！";