PHP Help From Book

[Nic, Val, Vic, Mara, Ecs & Alc]

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'] ;

$searchterm = trim($searchter m) ;

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

$searchtype = addslashes($sea rchtype) ;
$searchterm = addslashes($sea rchterm) ;

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

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

mysql_select_db ("tjc_books" );

$query = "SELECT * FROM books WHERE ".$searchty pe." LIKE
'%".$searchterm ."%'" ;
$result = mysql_query($qu ery) ;

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

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

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

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

?>

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

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

[Jamie Davison]

> 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'] ;

$searchterm = trim($searchter m) ;

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

$searchtype = addslashes($sea rchtype) ;
$searchterm = addslashes($sea rchterm) ;

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

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

mysql_select_db ("tjc_books" );

$query = "SELECT * FROM books WHERE ".$searchty pe." LIKE
'%".$searchterm ."%'" ;
$result = mysql_query($qu ery) ;

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

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

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

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

?>

First off, as a beginner, you should not be suppressing MySQL errors. The @
symbol in front of :
@ $db = mysql_pconnect( 'localhost', ...'); will suppress error
messages.

Use a function to return any specific MySQL errors:

For instance:

function the_error ($message) {
$mysql_error = mysql_errno() . ": " . mysql_error();
$page = getenv("REQUEST _URI");
$server = getenv("SERVER_ NAME");
echo "<h1>Sorry, an error has occured!</h1>\n<P>$messag e\n\n";
echo "<P><b>MySQ L Error Info</b><br>$mysql_er ror\n";

echo "<P><A HREF=\"mailto:y o*******@yourem ail.com?subject =Error on
http://$server$page&bo dy=Error Message: $message (mysql error info:
$mysql_error)\" >email the webmaster</a>";
exit;
}
//end error function
//Then connect to your db. pconnect is persistant (Do you need a persistant
connection? If not use mysql_connect.)

$db = mysql_connect(' localhost', 'yourusername', 'yourpass') ;

//Then your query
$sql = "SELECT * FROM yourdatabase";
result = mysql_query($sq l,$db) or the_error("Coul dn't execute get sector
types query: <pre>$sql</pre>");
^
^
Function Call

This will help you enormously for debugging . . .
-JD