这三个东西怎么搭配使用呢

<br />	$mysqli=new mysqli("localhost","root","123456","test");<br /><br />	if($mysqli->connect_error){<br />		die($mysql->connect_error);<br />	}<br />	//将提交设为 false(一旦提交,无法回滚)<br />	$mysqli->autocommit(false);<br />	//保存点 ，把当前记录保存<br />	$sql1="update account set balance=balance-1 where id=1";<br />	$sql2="update account set balance=balance+1 where id=2";<br /><br />	$b1=$mysqli->query($sql1);<br />	$b2=$mysqli->query($sql2);<br /><br />	if(!$b1<br><font color='#FF8000'>------解决思路----------------------</font><br>!$b2){<br />		//回滚<br />		$mysqli->rollback();<br />		echo "失败--".$mysqli->error;<br />	}else{<br />		//提交<br />		$mysqli->commit();<br />		echo "成功";<br />	}<br /><br />	$mysqli->close();<br />