<IfModule mod_rewrite.c>
    RewriteEngine on

    RewriteBase /

    # only if the requested file does not exists
    RewriteCond %{REQUEST_FILENAME} !-f

    # Store the current location in an environment variable CWD
    RewriteCond $0#%{REQUEST_URI} ([^#]*)#(.*)\1$
    RewriteRule ^.*$ - [E=CWD:%2]

    # Just by prefixing the environment variable, we can safely rewrite anything now
    RewriteRule ^([^/]*) %{ENV:CWD}index.php?database=$1 [QSA,L]
</IfModule>