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[SOLVED] Warning: mysql_num_rows(): supplied argument is not a valid MySQL result

sanderphp

By sanderphp
in PHP Coding Help

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sanderphp Member

sanderphp

Posted
Posted

I'm getting the following error on a login script from http://www.phpeasystep.com/workshopview.php?id=6

 

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/sanderan/public_html/php/cycling/checklogin.php on line 27

Wrong Username or Password

 

Is this really a password issue or something else? Here is my code.

 

<?php
ob_start();
$host="localhost"; // Host name 
$username="sanderan_stats"; // Mysql username 
$password="password"; // Mysql password 
$db_name="sanderan_cycling"; // Database name 
$tbl_name="riders"; // Table name 

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");

// Define $myusername and $mypassword 
$myusername=$_POST['myusername']; 
$mypassword=$_POST['mypassword']; 

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $myusername and $mypassword, table row must be 1 row

if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
header("location:login_success.php");
}
else {
echo "Wrong Username or Password";
}

ob_end_flush();
?>

moselkady Newbie

moselkady

Posted
Posted

 

Maybe you can print for us your query string as well as any errors from your query.

 

.....
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
print "$sql<br>";
$result=mysql_query($sql);
print mysql_error()."<br>";
.....

 

 

sanderphp Member

sanderphp

Posted
  • Author
Posted

Unless I misunderstood what you were asking for, I added your code into mine.

 

Here is the result:

 

SELECT * FROM riders WHERE username='' and password=''

Unknown column 'username' in 'where clause'

 

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/sanderan/public_html/php/cycling/checklogin.php on line 29

Wrong Username or Password

moselkady Newbie

moselkady

Posted
Posted

 

It appears that your table does not have a field called "username". As a result mysql_query($sql) fails and $result becomes invalid handle and gives the warning error when you use it afterwards.

 

Check your table definition for the "username" field and probably it is misspelled.

sanderphp Member

sanderphp

Posted
  • Author
Posted

aha.... I was using 'login' and the example was using username.

 

It now goes to the login_success.php page and shows me this. Anything to worry about or is this what I should be seeing?

 

// Check if session is not registered , redirect back to main page. // Put this code in first line of web page.

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/sanderan/public_html/php/cycling/login_success.php:3) in /home/sanderan/public_html/php/cycling/login_success.php on line 4

Login Successful

 

// Check if session is not registered , redirect back to main page. 
// Put this code in first line of web page. 
<? 
session_start();
if(!session_is_registered(myusername)){
header("location:main_login.php");
}
?>

<html>
<body>
Login Successful
</body>
</html>

sanderphp Member

sanderphp

Posted
  • Author
Posted

Here is all that I have in the login_success.php file

 

// Check if session is not registered , redirect back to main page. 
// Put this code in first line of web page. 
<? 
session_start();
if(!session_is_registered(myusername)){
header("location:main_login.php");
}
?>

<html>
<body>
Login Successful
</body>
</html>

AndyB Regular Member

AndyB

Posted
Posted 

<?
// Check if session is not registered , redirect back to main page. 
// Put this code in first line of web page.  
session_start();
if(!session_is_registered(myusername)){
header("location:main_login.php");
}
?>

<html>
<body>
Login Successful
</body>
</html>

 

The above works.

 

You needed to move the comment inside the php tags to stop it displaying - which is the output that caused the error.

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