PDO 事务

$dsn = ‘mysql:dbname=wxadmin;host=127.0.0.1‘;
$user = ‘root‘;
$password = ‘‘;


try{

    $pdo = new PDO($dsn,$user,$password);

    $pdo->exec("set names utf8");

    $pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION); #开启异常模式 ( 提示的错误信息更具体 )
    $pdo->setAttribute(PDO::ATTR_AUTOCOMMIT,0);                   #关闭自动提交 ( 使用事务前必须关闭 )

}catch(PDOException $es){

    echo ‘Error: ‘.$es->getMessage();

}


       #    id为1的用户  转账100元  给  id为2的用户


    try{

        $pdo->beginTransaction();

        $sql = ‘UPDATE sw_test SET num = num - 100 WHERE id = 1 AND num >= 800‘;

        $affected_rows = $pdo->exec($sql);

        if($affected_rows==false || $affected_rows===false){

            throw new PDOException("转出失败");

        }

        $sql = ‘UPDATE sw_test SET num = num + 100 WHERE 2id = 2‘;

        $affected_rows = $pdo->exec($sql);

        if($affected_rows==false || $affected_rows===false){

            throw new PDOException("转入失败");
        }

        $pdo->commit();

        echo ‘交易成功‘;

    }catch(PDOException $e){

        $pdo->rollback(); // 只要捕获异常则回滚

        echo $e->getMessage();

    }

    // 事务结束  重新开启自动提交
    $pdo->setAttribute(PDO::ATTR_AUTOCOMMIT,1);