<?php
//1、创建数据库连接对象
$mysqli = new MySQLi("localhost","root","123456","liuyan");
if($mysqli->connect_error){
 die($mysqli->connect_error);
}
$mysqli->query("set names 'GBK'");

$mysqli->autocommit(false);
//首先设置autocommit为false，也就是不自动提交

$sql1 = "update account set balance=balance-2 where id=1;";
$sql2 = "update account set balance=balance+2 where id=2;";
$res1 =$mysqli->query($sql1) or die($mysqli->error);
$res2 =$mysqli->query($sql2) or die($mysqli->error);

if(!$res1 || !$res2){
 echo "转账失败";
 $mysqli->rollback();//如果有一条不成功，则回滚
}else{
 $mysqli->commit();//两条语句都执行成功，则提交
 echo "转账成功";
}
?>