mod_rewrite empties QUERY_STRING if starting with number [closed]

Question

I have a simple database query script alongside with my WordPress installation, to which I pass a parameter using the following URL: http://example.com/db/?p=foo.

My database script reads the parameter with

$pid = $_GET['p'];

Everthing works fine, IF the parameter does NOT START WITH A NUMBER.

so, ?p=foo is ok, but ?p=3poo is EMPTY.

Edit: I confirmed this by changing my script to

<?php
print_r($_GET);
exit;

which gives as an output

Array ( )

I suspect that it's the mod_rewrite who suppresses the parameters starting with a number. But I have no clue why, and how I can change this behavior. Any ideas?

Edit: Unfortunately, I can not change the name of the parameter 'p', nor can I change the values of the parameter so they do not start with numbers, since the URLs where released as QR-tags to the public already, so I need a workaround to make this exact URLs work.

Here is my .htaccess file in the root folder (edited as suggested by MrWhite, works as expected)

<IfModule mod_rewrite.c>

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

</IfModule>

Answer 1

Thanks to Tom, I looked more carefully to the plugins.

And I can confirm that the problem is NOT RELATED to mod_rewrite, but to a plugin conflict. (sorry that I posted such a suspicion, but I read somewhere a very similar problem that was explained like that.)

Deactivating plugin by plugin, I found that one you made this behaviour. Still no clue why, but at least I have now a workaround: deactivating this plugin.

Thanks Tom and all the others for your help!

Answer 2

Finally, completely understood and solved the problem using @MrWhite 's advice to use mod_rewrite to rewrite the query. Thanks!

To explain:

1) My http://example.com/db/?p=foo is (and this I didn't realise) actually not accessing the dbquery.php script, but a wordpress-page "db", which calls the dbquery.php script using the Plugin "INCLUDEME".

2) So, the query-string is first processed by Wordpress (or whatever, don't know the right term), and since - as @Tom J Nowell pointed out - my parameter "p" has a special meaning, it was emptied by "Wordpress", and already no query string made it to the plugin. So it was not the plugins fault.

3) Conclusion: not mod_rewrite, not the plugin, not the value starting with a number was the problem, but the simple fact that I used "p" was the source of the problem.

4) The solution consisted in:

a) rename the WP-page "db" into "nachverfolgbarkeit"

b) create a directory called "db"

c) place a .htaccess file in db containing the below redirection, to redirect from db to the new page "nachverfolgbarkeit" (which calls dbquery.php using INCLUDEME); and correcting the parameter from "p" to "pid"

Not very nice patch, but it works well. So my advice to every reader: "Never use p as a parametername" ...

Thanks to all for their help. Nounours

RewriteEngine On
RewriteCond %{QUERY_STRING} ^p=(.*)$
RewriteRule ^$ /nachverfolgbarkeit/?pid=%1   [R=301]