PHP使用pdo实现事务处理操作示例

<?php
$dsn   = "mysql:dbname=pdo;host=localhost";
$user   = "root";
$password = "root";
$dbh   = new PDO($dsn, $user, $password);
//使用事务之前，要先关闭自动提交。不关闭的话，出现异常的时候没法回滚。
//据手册描述，ATTR_AUTOCOMMIT属性只在mysql，OCI(oracle),firebird三种数据库中可用
$dbh->setAttribute(PDO::ATTR_AUTOCOMMIT, 0);
$cash = 100;
try {
  $dbh->beginTransaction();
  //用户A账户扣除100
  $sqlcmd    = "update transaction set useraccount=useraccount - {$cash} where username ='A'";
  $affected_rows = $dbh->exec($sqlcmd);
  if ($affected_rows > 0) {
    echo "用户A账户扣除成功" . "<br>";
  } else {
    throw new Exception("用户A账户扣除失败");
  }
  //用户B账户增加100
  $affected_rows = $dbh->exec("update transaction set useraccount=useraccount+{$cash} where username ='B'");
  if ($affected_rows > 0) {
    echo "用户B账户增加成功" . "<br>";
  } else {
    throw new Exception("用户B账户增加失败");
  }
  echo "转账成功";
  //若前面两个步骤都成功，则提交事务
  $dbh->commit();
}
catch (PDOException $e) //若前面两个步骤中出现了异常，则回滚
  {
  echo $e->getMessage();
  $dbh->rollback();
}
//对事物的使用结束之后，重新开启自动提交
$dbh->setAttribute(PDO::ATTR_AUTOCOMMIT, 1);
?>