RewriteCond %{QUERY_STRING} in mod_rewrite (dynamic to static URL) not working
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Hello all overflowers,

Htaccess/mod-rewrite question.

As I have encountered very luck with managing to get querystrings to redirect correctly previously just passing querystring parameters, and the over-arching advice across this site and webmasterworld for querystring redirection seems to be "deal with it as a RewriteCond querystring", I'm trying to use the following type rule for a set of about 10 URLs.

Example URL:

    http://www.example.com/event_book.asp?sInstance=1&EventID=139

What I have so far:
    
    RewriteCond %{QUERY_STRING} ^event_book.asp\?sInstance=1&EventID=139  
    RewriteRule /clean-landing-url/ [NC,R=301,L]

- note the backslash prior to the start of the querystring to try and escape the question mark.

So, what I want to happen is

    http://www.site.com/event_book.asp?sInstance=1&EventID=139 301> http://www.site.com/clean-landing-url

but instead what is happening is this:

    http://www.site.com/event_book.asp?sInstance=1&EventID=139 301> http://www.site.com/event_book.asp/?sInstance=1&EventID=139

It's appending a forward slash just before the querystring, and then resolving the full URL (obviously, 404ing.)

What am I missing? Is it a regex issue with the actual %{QUERY_STRING} parameter?

Thanks in advance!