.htaccess - need help. rewriterule not working with /? -

my url

http://example.com/?aff_id=username

and want

http://example.com/?ap_id=username

i have tried possible ways no luck. if removed ? (question mark) works want ? in url. know regular expression tried escape no luck.

you can use following in /.htaccess file:

rewriteengine on rewritecond %{query_string} aff_id=([\w]+) [nc] rewriterule ^$ /?ap_id=%1 [r,l]

if make redirect permanent, change r r=301.

Braziel