Mysql_num_rows() not working

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March 19th, 2008, 11:24 AM

hello123456789

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General - Mysql_num_rows() not working

I keep getting an error that says "Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in C:\xampp\htdocs\projectmanager\upload.php on line 14"

the code is as follows:

PHP Code:


		
			
 $sql = "SELECT * FROM members WHERE project_id = ".$_GET['project_id']." AND username = ".$_SESSION['USERNAME'].";"; /*line 12*/

//line 13

$numrows = mysql_num_rows($sql);/*line 14*/

I'm not really sure what is wrong, any help would be greatly appreciated. Thanks!

March 19th, 2008, 11:41 AM

ehsan

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You are not executing the query!!

PHP Code:


		
			
 $sql = mysql_query("SELECT....

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March 19th, 2008, 05:42 PM

hello123456789

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Well, I edited the code so it looks like this:

PHP Code:


		
			
 $sql = "SELECT * FROM members WHERE project_id = ".$_GET['project_id']." AND username = ".$_SESSION['USERNAME'].";";



$result = mysql_query($sql);

$numrows = mysql_num_rows($result);

but i still get the same error. Am I using the query correctly?

March 20th, 2008, 07:12 AM

ehsan

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Try to print mysql_error() which will tell you if there's anything wrong with the SQL. As far I think either $_GET['project_id'] or $_SESSION['USERNAME'] is blank. There's one more possibility. I think you "username" field is either a char or varchar type, therefore, you will need quotation in the SQL. Something similar to the following:

PHP Code:


		
			
 $sql = "SELECT * FROM members WHERE project_id = ".$_GET['project_id']." AND username = '".$_SESSION['USERNAME']."';";

Notice the SINGLE QUOTES username = '".$_SESSION['USERNAME']."'

I will suggest, before you go in the query, check if both the username and project_id are not empty. Printing any possible mysql error will help you debug better.

PHP Code:


		
			
 $result = mysql_query($sql); 

echo mysql_error();

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