Warning: mysql_num_rows() expects parameter 1 to be resource. how to solve this warning?

Question

I have crated one log in form in which i want that user can change the password for that i have created as below

if(isset($_SESSION['user_name']))
{
    $password=$_POST['new_password'];
    $query="select * from login where  username = '$_SESSION[user_name]' and password='" . md5($_SESSION['password']) . "'  ";
    echo $query;
    $result=mysql_query($query);
    //echo "abc";
    if(mysql_num_rows($result))
    {   
        $row=mysql_fetch_array($result);
        $pass=$row['password'];
        if($pass==$password)
        {
            $query2="UPDATE login SET password='$password' WHERE username='$_SESSION[user_name]'";
            echo $query2;
            echo "Password changed successfully";
        }
        else
        {
            echo "You entered wrong current password";
        }
    }

}

but the Warning mysql_num_rows() expects parameter 1 to be resource. is coming on the line "if(mysql_num_rows($result))". what is the solution for that?

this is not fault. It gives perfect output if echo $query..... — Pradeep, Oct 29 '13 at 11:32
See : http://stackoverflow.com/questions/5473981/warning-mysql-fetch-array-expects-parameter-1-to-be-resource-boolean-given-i — Roy M J, Oct 29 '13 at 11:33

score 0 · Answer 1 · answered Oct 29 '13 at 11:32

change this:

 $query="select * from login where  username = '$_SESSION[user_name]' and password='" . md5($_SESSION['password']) . "'  ";

To:

$query="select * from login where  username = '".$_SESSION['user_name']."' and password='" . md5($_SESSION['password']) . "'  ";

score 0 · Answer 2 · answered Oct 29 '13 at 11:33

0

Your query ($query) is failing and therefore not producing a query resource, its because of the quotes '".$_SESSION[user_name]."'

answered Oct 29 '13 at 11:33

user2092317

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it is ok but problem is on this line -if(mysql_num_rows($result))..... – Pradeep Oct 29 '13 at 11:35
please echo the query here – user2092317 Oct 29 '13 at 11:37
try `mysql_query or die(mysql_error());` to check if your query failed – user2092317 Oct 29 '13 at 11:37

score 0 · Answer 3 · answered Oct 29 '13 at 11:36

$result in your case may contain resource and false as well.
You see this message when you got false, means your query has failed.
Simple solution is to add check for it

if ($result){
  if(mysql_num_rows($result))
  ...
} else {
  // FIXME: Handle this exception
  echo("Query has failed");
}

Also, you should know that mysql_query is deprecated. Consider switching to MySQLi or PDO_MySQL

Warning: mysql_num_rows() expects parameter 1 to be resource. how to solve this warning?

4 Answers4