Php / MYSQL problems. mysql_num_rows() returns 0

Question

I am trying to create a logging in system for my website. this is what i have.

    include('MYSQL_connect_userdata.php');
    $query = "SELECT * FROM userinfo WHERE username = '$username' AND password = '$password' ";
    $result = mysql_query($query) or die("cant find table");
    $count2 = mysql_num_rows($result);
    $resultarray = mysql_fetch_array($result);
    echo "SELECT * FROM userinfo WHERE username = '$username' AND password = '$password' ";

MYSQL_connect_userdata.php connects to the mysql server and selects the database.

When I paste the output of the echo "SELECT * FROM userinfo WHERE username = '$username' AND password = '$password' ";

phpmyadmin returns the row that i am looking for. (contains a username and password")

for some reason mysql_num_rows($result) is returning 0 even when the inputs are the correct values. the inputs are taken using $_POST like this at the top of the php file

$username = $_POST['username'];
$password = $_POST['password'];

If I change the query to exclude the "AND password = '$password' "; part then the page works as intended and mysql_num_rows returns 1.

any ideas whats going on? im rlly new to php so extra explaination would be appreciated. Thanks.

Your application is a call for SQL injection

jachguate
– jachguate

2012-12-07 02:14:48 +00:00
Commented Dec 7, 2012 at 2:14 — jachguate
– jachguate, Commented Dec 7, 2012 at 2:14
Echo the query to see what it looks like in the script

jmm
– jmm

2012-12-07 02:15:20 +00:00
Commented Dec 7, 2012 at 2:15 — jmm
– jmm, Commented Dec 7, 2012 at 2:15

rizon · Accepted Answer · 2012-12-07 02:26:51Z

1

$con = mysql_connect("localhost", "peter", "abc123");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

$db_selected = mysql_select_db("test_db",$con);

$sql = "SELECT * FROM person";


//Your missing the connection , store in a variable
$result = mysql_query($sql,$con);

echo mysql_num_rows($result);

mysql_close($con);

answered Dec 7, 2012 at 2:26

rizon

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