Help I have an error message using PHP quotWarning mysql num rows supplied argument is not a valid MySQL result resource in...quot

Questions

I m trying to run a query in MySql database but I have the same warning everytime. Can someone help.

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX/public_html/login.php on line 279 The Username you supplied does not exist!

I have highlighted line 279 with ++++++++++++$num = mysql_num_rows($res);++++++++++++

Please let me know how I can rectify the problem.

<?php
  //If the user has submitted the form
  if($_POST[ submit ]) {
    //protect the posted value then store them to variables
    $username = protect($_POST[ username ]);
    $password = protect($_POST[ password ]);

    //Check if the username or password boxes were not filled in
    if(!$username || !$password) {
      //if not display an error message
      echo "<center>You need to fill in a <b>Username</b> and a <b>Password</b>!</center>";
    } else {
      //if the were continue checking

      //select all rows from the table where the username matches the one entered by the user
      $res = mysql_query("SELECT * 
                            FROM `users` 
                           WHERE `username` =  ".$username." ");
      ++++++++++++++$num = mysql_num_rows($res);++++++++++++++++++

      //check if there was not a match
      if($num == 0) {
        //if not display an error message
        echo "<center>The <b>Username</b> you supplied does not exist!</center>";
      } else {
        //if there was a match continue checking

        //select all rows where the username and password match the ones submitted by the user
        $res = mysql_query("SELECT * FROM `users` 
                             WHERE `username` =  ".$username."  
                               AND `password` =  ".$password." ");
        $num = mysql_num_rows($res);

        //check if there was not a match
        if($num == 0) {
          //if not display error message
          echo "<center>The <b>Password</b> you supplied does not match the one for that username!</center>";
        } else {
                    //if there was continue checking

                    //split all fields fom the correct row into an associative array
                    $row = mysql_fetch_assoc($res);

                    //check to see if the user has not activated their account yet
                    if($row[ active ] != 1){
                        //if not display error message
                        echo "<center>You have not yet <b>Activated</b> your account!</center>";
                    }else{
                        //if they have log them in

                        //set the login session storing there id - we use this to see if they are logged in or not
                        $_SESSION[ uid ] = $row[ id ];
                        //show message
                        echo "<center>You have successfully logged in!</center>";

                        //update the online field to 50 seconds into the future
                        $time = date( U )+50;
                        mysql_query("UPDATE `users` SET `online` =  ".$time."  WHERE `id` =  ".$_SESSION[ uid ]." ");

                        //redirect them to the usersonline page
                        header( Location: usersOnline.php );
                    }
                }
            }
        }
    }

    ?>

Answers

http://php.net/mysql-error http://php.net/mysql-error

$res = mysql_query("SELECT * FROM `users` WHERE `username` =  ".$username." ");
if ($res === false) {
    echo mysql_errno() .  :   . mysql_error();
    exit;
}
$num = mysql_num_rows($res);

Source

License : cc by-sa 3.0

http://stackoverflow.com/questions/6170735/help-i-have-an-error-message-using-php-warning-mysql-num-rows-supplied-argu

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