1. <?php
  2. session_start();
  3. if (isset($_POST['userid']) && isset($_POST['password'])) {
  4. $userid= $_POST['userid'];
  5. $password= $_POST['password'];
  7. $db_conn = new mysqli('localhost', 'webauth', 'webauth', 'auth');
  8. if (mysqli_connect_errno()) {
  9. echo 'Connection failed'.mysqli_connect_errno();
  10. exit();
  11. # code...
  12. }
  14. $query= 'select * from authorized_users'."where name= '".$userid."'"."&& password= sha1('".$password."')";
  15. $result= $db_conn->query($query);
  16. if ($result->num_rows) {
  17. $_SESSION['valid_user']= $userid;
  18. # code...
  19. }
  20. $db_conn->close();
  21. }
  22. ?>
  24. <html>
  25. <body>
  26. <h1>Home page</h1>
  27. <?php
  28. if (isset($_SESSION['valid_user'])) {
  29. echo "You are logged in as: ".$_SESSION['valid_user'].'<br />';
  30. echo '<a href= "logout.php">Log Out</a>';
  31. }
  33. else{
  34. if(isset($userid)){
  35. echo 'Could not log you in.<br />';
  36. }
  37. else {
  38. echo 'You are not logged in.<br />';
  39. }
  40. echo '<form method= "post" action= "authmain.php">';
  41. echo '<table>';
  42. echo '<tr><td>Userid: </td>';
  43. echo '<td><input type= "text" name= "userid"></td></tr>';
  44. echo '<tr><td>Password: </td>';
  45. echo '<td><input type= "password" name= "password"></td></tr>';
  46. echo '<tr><td colspan= "2" align= "center">';
  47. echo '<input type= "submit" value= "log in"></td></tr>';
  48. echo '</table></form>';
  49. }
  50. ?>
  51. <br />
  52. <a href="members_only.php">Members section</a>
  53. </body>
  54. </html>

if ($result->num_rows) 返回NULL，怎么回事