PHP Help From Book

Does anyone know what's wrong with this code? I just started learning php &
mysql from a book and this code is copied directly from it, yet it still
fails to work... I always get the following error:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result
resource in /home/tjc/public_html/results.php on line 40


<?php
// create short varibles names
$searchtype = $HTTP_POST_VARS['searchtype'] ;
$searchterm = $HTTP_POST_VARS['searchterm'] ;

$searchterm = trim($searchterm) ;

if (!$searchtype || !$searchterm)
{
echo "No search details entered" ;
exit ;
}

$searchtype = addslashes($searchtype) ;
$searchterm = addslashes($searchterm) ;

@ $db = mysql_pconnect('localhost', 'tjc_bookorama', 'bookorama123') ;

if (!$db)
{
echo "Error: Could not connect to db" ;
exit ;
}

mysql_select_db ("tjc_books");

$query = "SELECT * FROM books WHERE ".$searchtype." LIKE
'%".$searchterm."%'" ;
$result = mysql_query($query) ;

$num_results = mysql_num_rows($result); // line 40

echo "<p>Number of books found: ".$num_results."</p>" ;

for ($i = 0; $i <num_results; $i++)
{ {
$row = mysql_fetch_array($result) ;
echo '<p><strong>'.($i + 1).'. Title: ' ;
echo htmlspecialchars(stripslashes($row['title'])) ;
echo '</strong><br />Author: ' ;
echo stripslashes($row['author']) ;
echo '<br />ISBN: ' ;

echo stripslashes($row['isbn']) ;
echo '<br />Price: ' ;
echo stripslashes($row['price']) ;
echo '</p>' ;
}

?>

************************************************** **************************
*****

QOTSA: "Nicotine, Valium, Vicodin, Marijuana, Ecstacy and Alcohol"
Einstein: "Imagination is More Important Than Knowledge"

"Nic, Val, Vic, Mara, Ecs & Alc" <ilove@spam.org> wrote in message
news:3f3f6c04$0$960$cc9e4d1f@news.dial.pipex.com.. .
> Does anyone know what's wrong with this code? I just started learning php
&
> mysql from a book and this code is copied directly from it, yet it still
> fails to work... I always get the following error:
>
> Warning: mysql_num_rows(): supplied argument is not a valid MySQL result
> resource in /home/tjc/public_html/results.php on line 40

Probably your db query is not ok, try inserting echo "|$query|"; after the
following line.

> $query = "SELECT * FROM books WHERE ".$searchtype." LIKE
'%".$searchterm."%'" ;

probably is either $searchtype or $searchterm something silly or empty.
There are a few possible causes, like for instance the page from which you
are posting does not have variables seachterm or searchtype in the form, or
they are named differently. Or you are trying to access the page without
posting

rush
--
http://www.templatetamer.com/

Ah, yes there is also one obvious error in the code, at the beggining you
need to declare $HTTP_POST_VARS as global:

global $HTTP_POST_VARS;

Btw, which book is that?

rush
--
http://www.templatetamer.com/

It looks like Advanced PHP For Flash, a Friends of Ed title? Am I
correct????
John
"rush" <pipa@rush.avalon.hr> wrote in message
news:bho4k1$7u9$1@ls219.htnet.hr...
> Ah, yes there is also one obvious error in the code, at the beggining you
> need to declare $HTTP_POST_VARS as global:
>
> global $HTTP_POST_VARS;
>
> Btw, which book is that?
>
> rush
> --
> http://www.templatetamer.com/
>
>
>