how to make url query string more safe from sql injection

Thanks Michael
Had a look and still can't work out how to apply it to my code.
My function is:
function check_input($value)
{
// Stripslashes
if (get_magic_quotes_gpc())
{
$value = stripslashes($value);
}
// Quote if not a number
if (!is_numeric($value))
{
$value = "'" . mysql_real_escape_string($value) . "'";
}
return $value;
}


and I know how to apply the function but this is my recordset (MX7)
$Category_r_search = "=";
if (isset($_GET['Category'])) {
$Category_r_search = (get_magic_quotes_gpc()) ? $_GET['Category'] : addslashes($_GET['Category']);
}
$Type_r_search = "=";
if (isset($_GET['Type'])) {
$Type_r_search = (get_magic_quotes_gpc()) ? $_GET['Type'] : addslashes($_GET['Type']);
}
mysql_select_db($database_config, $config);
$query_r_search = sprintf("SELECT* FROM listing WHERE listing.status = 'notactive' AND listing.inv_country = 'Australia' AND (listing.classcatid LIKE '%%%s%%' AND listing.industryid LIKE '%%%s%%') ORDER BY listing.inv_country ASC", $Category_r_search,$Type_r_search);
$r_search = mysql_query($query_r_search, $config) or die(mysql_error());
$row_r_search = mysql_fetch_assoc($r_search);
$totalRows_r_search = mysql_num_rows($r_search);

And this is the url string for the search results:

<a href="result.php?Category=Freelance&Type=Beauty">Beauty</a>

As I am not using a $Category or $Type how can I get this to work with the function?
Yes I am echoing out the results but I thought the way you would use the function would be e.g.
$Category = check_input($_GET['Category']);
But I am not using $Category anywhere and can't see where to.

Hope that makes sense....

.oO(jjjhbj111)

>Hi is there a way to prevent sql injection from my search results using a url
>query e.g.
> Thanks - looked up in google but didn't find what I was looking for or could
>use in this instance.
>
> <a href="results.php?Category=Beauty&Type=For%20Sale">Beauty</a>

Users can submit whatever they want to your site. It's your script that
is responsible for handling the data appropriately, especially if it's
meant to be sent to a database.

Keywords for further research:

* mysql_real_escape_string()
* prepared statements

Micha