I get an annoying error on my login system

Question

I am trying to make a login system for my website but there is an error comming every time i run it that says:

Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in C:\xampp\htdocs\login_system\includes\login.php on line 46.

I'v searched around the web for a sulution and tryed out a few things but it doesn't seem to be working so please help me if someone can figure it out

Here is my code:

<?php
error_reporting (E_ALL ^ E_NOTICE);
session_start();
?>
<!doctype html>

<html>
<head>
    <meta charset="utf-8">
    <title>Untitled Document</title>
</head>


<body>
    <?php

        $form = "<form action='login.php' method='post'>
            <table>
                <tr>
                    <td>Brugernavn:</td>
                    <td><input type='text' name='bruger' /></td>
                </tr>
                <tr>
                    <td>Password:</td>
                    <td><input type='password' name='password' /></td>
                </tr>
                <tr>
                    <td><input type='submit' name='logind_btn' value='Log ind' /></td>
                </tr>
            </table>
        </form>";


        if($_POST['logind_btn']){
                $bruger = $_POST['bruger'];
                $password = $_POST['password'];

                if($bruger){
                    if($password){
                        require("tilslut.php");

                        $password = md5(md5("dj4fJsd".$password."gd34aH"));
                        // vær sikker på login info er korrekt
                        $query = mysql_query("SELECT * FROM brugere WHERE brugernavn='$bruger'");
                        $numrows = mysql_num_rows($query);
                        if ($numrows == 1){
                            $row = mysql_fetch_assoc($query);
                            $dbbrugerID = $row['id'];
                            $dbbruger = $row['brugernavn'];
                            $dbpass   = $row['password'];
                            $dbactive = $row['active'];

                            if($password == $dbpass){
                                if($dbactive == 1){

                                    $_SESSION['brugerID'] = $dbbrugerID;
                                    $_SESSION['brugernavn'] = $dbbruger;

                                    echo "Du er nu logget ind som <b>$dbbruger</b>. <a href='medlem.php'>Klik her</a> for at gå til Medlems siden!";
                                }
                                else
                                    echo "Du skal aktivere din konto for at logge ind. $form";

                            }
                            else
                                echo "Du intastede ikke det korrekte password. $form";

                        }
                        else
                            echo "Det intastede brugernavn blev ikke fundet. $form";


                        mysql_close();
                    }
                    else
                        echo "Du skal skrive dit password! $form";

                }
                else
                    echo "Du skal skrive et brugernavn! $form";

        }
        else
            echo $form;


    ?>

your query is failing, try to catch the error using `echo mysql_error($link)` where $link is the connection — Emilio Gort, Nov 18 '13 at 20:03
as side note mysql_* functions are deprecated, look the red box at the top of the page http://us3.php.net/mysql_error — Emilio Gort, Nov 18 '13 at 20:04

score 3 · Accepted Answer · edited Jun 20 '20 at 09:12

Let's take a closer look at that error message of yours:

Warning: mysql_num_rows() expects ...

AHA! So mysql_num_rows() is causing problems. Good thing you only have it once in your code, since I didn't want to count your lines finding the one causing this error

... expects parameter 1 to be resource, boolean given ...

Oh, so something seems to be wrong with the parameter. Lets look closely at your code:

$query = mysql_query(...);
$numrows = mysql_num_rows($query);

So $query is a boolean (true/false) - how can this be? Right, manual always knows best

For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error.

For other type of SQL statements, INSERT, UPDATE, DELETE, DROP, etc, mysql_query() returns TRUE on success or FALSE on error.

mysql_query() will also fail and return FALSE if the user does not have permission to access the table(s) referenced by the query.

So the problem is that your query probably fails and hence returns false which is not a valid resource but rather a boolean

Also keep in mind that mysql_* functions are officially deprecated and hence should not be used in new code. You can use PDO or MySQLi instead. See this answer on SO for more information.

+1. very educational, just try adding how to catch the errors and motivate the op to use another option like mysqli or PDO — Emilio Gort, Nov 18 '13 at 20:06

score 1 · Answer 2 · answered Nov 18 '13 at 20:00

1

it Looks like the query-function returs false (query failed) and false is also given as Parameter in mysql_num_rows. there are several possible ways why the query could fail, maybe the database does not exist or something else.

answered Nov 18 '13 at 20:00

Sirac

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I get an annoying error on my login system

2 Answers2