Use mod_rewrite, yet keeping the "?"

I'm wasting hours here with .htaccess to make those nice looking URLs possible and reached a dead end. This is what worked for me in the past:

RewriteRule ^(.*)\?*$ app.php?_target=$1 [L]

Now I would like to extend this rule to support URLs like this:

http://mydomain.com/articles/regex-cheatsheet/?sortby=expression&order=asc&filter=numeric

Here is a nice explanation for why I would like doing this. My rule looks like this now:

RewriteRule ^(.*)\?(.*)$ app.php?_target=$1&$2 [L]

I've validated this expression, as I am no regEx expert and it seems OK. Bu开发者_开发百科t, of course, it doesn't work :/

So does anyone know what I am doing wrong?

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Use the QSA (Query String Append) flag:

RewriteRule (.*) app.php?_target=$1 [L,QSA]