<?
  require_once('conn.php');
  session_start();
  $username=$_POST['username'];
  $password=$_POST['password'];
  $exec="select * from admin where username='".$username."'";
  if($result=mysql_query($exec))
  {
  if($rs=mysql_fetch_object($result))
  {
    if($rs->password==$password)        //这里的->这个东西是什么意思？？
    {
      $_SESSION['adminname']=$username;  //这句话在这里有什么用呢？？
      header("location:index.php");
    }
    else
    {
      echo "<script>alert('Password Check Error!');location.href='login.php';</script>";
    }
  }
  else
  {
  echo "<script>alert('Username Check Error!');location.href='login.php';</script>";
  }
  }
  else
  {echo "<script>alert('Database Connection Error!');location.href='login.php';</script>";
}

  ?>