How to secure .htaccess links to user profiles? (vanity url)

[ilya Kraft]

Hello,

I recently decided to make .htaccess links to my user profiles so they would look something like

http://mywebsite.com/username

Right now I am using id to filter users, like this

http://mywebsite.com/profile.php?id=1

But I will need to change id to username, like so

http://mywebsite/profile.php?username=theus er

And then I would use .htaccess stuff to transform it to example mentioned at the begging.
Right now I am concerned about security, because when I was using id to filter profile page I used:

$id = preg_replace('#[^0-9]#i', '', $_GET['id']);

That filtered everything but numbers from id, to make it secure against SQL injection, but now when I filter by username it is not an option.

I am worried that someone could do something like this:

http://mywebsite/username, DROPDATABASE

And that DROPDATABASE thing could screw things up for me.

So could anyone suggest ideas and if possible examples of securing this? And if you have any questions or do not understand something of what I wrote please ask them ))))

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This is .htaccess code that I found and would probably use to accomplish my task.

Options +FollowSymLinks 
RewriteEngine On

RewriteCond %{SCRIPT_FILENAME} !-d 
RewriteCond %{SCRIPT_FILENAME} !-f

RewriteRule ^(\w+)$ ./index.php?username=$1

[Markus]

Ideally you would use a library such as PDO which provides prepared statements that are secured against attacks of this nature. In any case, the documentation provides information on protecting yourself against SQL Injection.

[ilya Kraft]

Hi,

Right I did a research about PDO, but I realized that it is too confusing to me, I'm not that advanced yet, just started couple months ago, so if it's not hard could you please tell me more about PDO. I also took a look at link you provided, but it only shows examples of unsecured stuff there, I was not able to find anything helpful. Well maybe this type of securing is too hard for me ))) I might stay with my old system a bit longer...