mysql_num_rows PHP

Question

elseif(isset($_POST['submit']))
{
    // Look for their user
    $lookuser = mysql_query("SELECT * FROM `users` WHERE username='". mysql_escape_string($_POST['username']) ."'");
    // If we find a row
    if(mysql_num_rows($lookuser) > 0)

But my else for that, echos: An error has occured. <br> If you are sure you entered your username correctly, please contact an administrator.

I've tried to echo $_POST['username']; all works out fine. I've made sure my user exists, that works out fine.

The PHP error I get: Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in password.php on line 23

You are not doing any error checking in your query. Why not? It's no wonder it breaks with that error if the query fails. This reference question shows how: http://stackoverflow.com/questions/6198104/reference-what-is-a-perfect-code-sample-using-the-mysql-extension — Pekka, Mar 19 '12 at 22:16
Have you echoed mysql_error()? $lookuser = mysql_query("SELECT * FROM `users` WHERE username='". mysql_escape_string($_POST['username']) ."'") or die(mysql_error()); — Luke Shaheen, Mar 19 '12 at 22:17
Sidenote: use mysql_real_escape_string() at least,if you want to stick to the mysql_* family — Damien Pirsy, Mar 19 '12 at 22:17
@RichBradshaw what more code would you need? The error is pretty clear — Damien Pirsy, Mar 19 '12 at 22:18
Do not use `mysql_escape_string()`, it is deprecated because it does not work properly. Use `mysql_real_escape_string()` instead. — Arjan, Mar 19 '12 at 22:19
possible duplicate of [PHP / MYSSQL error: mysql_num_rows(): supplied argument is not a valid](http://stackoverflow.com/questions/7995001/php-myssql-error-mysql-num-rows-supplied-argument-is-not-a-valid) — Marc B, Mar 19 '12 at 22:26
Better yet, don't use mysql_* at all -- it's all ancient, and barely supported. mysqli does everything mysql does, plus it offers support for prepared statements (which make escaping unnecessary for most use cases). — cHao, Mar 19 '12 at 23:04

score 1 · Answer 1 · edited Mar 19 '12 at 22:29

1

Php.net says this about the return value of mysql_query:

For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error.

If you're getting a boolean, it's because there's a mysql error. Use mysql_error() to print the error, it'll help you diagnose the issue.

edited Mar 19 '12 at 22:29

konsolenfreddy

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answered Mar 19 '12 at 22:19

FrankieTheKneeMan

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score 0 · Accepted Answer · edited Mar 19 '12 at 22:28

0

You probably have an error in your sql query. To be sure of that, echo after your mysql_query mysql_error().

edited Mar 19 '12 at 22:28

konsolenfreddy

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answered Mar 19 '12 at 22:18

haltabush

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mysql_num_rows PHP

2 Answers2