php表单验证作业 辰星 日常感谢老大桐镜！！ - 已锁定

<?php
    $user=($_POST['u']);
 $pass=($_POST['p']);
 $rr="/\'|\"|and|union|by|select|script/i";
 if(preg_match($rr,$user)){
 echo "<script>alert('你在干嘛？')</script>";
 }echo "<meta http-equiv='Content-Type'' content='text/html; charset=utf-8'>";    if(preg_match($rr,$pass)){
    echo "<script>alert('你在干嘛？')</script>";
}  echo "<meta http-equiv='Content-Type'' content='text/html; charset=utf-8'>";
    if(!empty($user) and !empty($pass)){
    #$pass=md5($pass);
 $con=mysqli_connect('127.0.0.1','root','root','test');
 mysqli_query($con,"set names 'utf8'");
 $sql="SELECT * FROM testtable WHERE (username='$user') AND (password='$pass')";
 $re=mysqli_query($con,$sql);
    $rs=mysqli_fetch_array($re); if(!empty($rs)){
  echo "登录成功";
  mysqli_close($con);
 }else{
  echo "用户或密码错误";
 }
 
 }
 else{
  echo "用户ming或密码为空";
 }
 ?>