<?php
require_once("database.php");
$con = get_connection( );
$sql="select * from teacher where teacher.teacher_id='".$_SESSION["account_no"]."'";
$results=@$con->query($sql)or die("执行'" . $sql . "'错误!");
$n = @$results->num_rows;
if($n=0)
{header("Location:index.php?url=stu_score.php");}
else{echo $n;};
?>
这里$n已经等于0了,就是不转是if的问题吗?