mod_rewrite and redirect causing loop - .htaccess

Question

I have problem when I try to redirect and rewrite together.
I have site example.com/show_table.php?table=12 (max 99 tables). I wanted nice links, so I got this .htacces rw rule:
RewriteRule ^table/([0-9]{1,2})$ show_table.php?table=$1 [L,NC]
Now are links something like example.com/table/12 - it's definitely OK. But I want all old links redirect to new format. So I use Redirect 301, I added to .htaccess this code:
RewriteCond %{REQUEST_URI} show_table.php
RewriteCond %{QUERY_STRING} ^table=([0-9]{1,2})$
RewriteRule ^show_table\.php$ http://example.com/table/%1? [L,R=301,NC]
But when I visit example.com/show_table.php?table=12, I receive just redir-loop. I don't understant - the first is rewrite, the second is redirection, there ain't no two redirections. Do You see any error?
Thanks!

Answer 1

Instead of checking REQUEST_URI in the condition, you need to be checking in THE_REQUEST (which contains the full original HTTP request, like GET /show_table.php HTTP/1.1). When Apache performs the rewrite, it changes REQUEST_URI, so to the rewritten value, and that sends you into a loop.
# Match show_table.php in the input request
RewriteCond %{THE_REQUEST} /show_table\.php
RewriteCond %{QUERY_STRING} ^table=([0-9]{1,2})$
# Do a full redirection to the new URL
RewriteRule ^show_table\.php$ http://example.com/table/%1? [L,R=301,NC]
# Then apply the internal rewrite as you already have working
RewriteRule ^table/([0-9]{1,2})$ show_table.php?table=$1 [L,NC]
You could get more specific in the %{THE_REQUEST} condition, but it should be sufficient and not harmful to use show_table\.php as the expression.
You'll want to read over the notes on THE_REQUEST over at Apache's RewriteCond documentation.
Note: Technically, you can capture the query string in the same RewriteCond and reduce it to just one condition. This is a little shorter:
# THE_REQUEST will include the query string so you can get it here.
RewriteCond %{THE_REQUEST} /show_table\.php\?table=([0-9]{1,2})
RewriteRule ^show_table\.php$ http://example.com/table/%1? [L,R=301,NC]