.htaccess issue, need a help plz.

From my Permalink Settings, I want to use "Post name". To use it, I need to copy some lines at my .htaccess.

The problem is, when I copy that part of lines at my .htaccess file, I got error to visit my forum.

My forum is in root directory, and my wp blog is in "root/db". Here is my recent .htaccess file without any error.

Code:

#    Mod_security can interfere with uploading of content such as attachments. If you
#    cannot attach files, remove the "#" from the lines below.
#<IfModule mod_security.c>
#    SecFilterEngine Off
#    SecFilterScanPOST Off
#</IfModule>
 
ErrorDocument 401 default
ErrorDocument 403 default
ErrorDocument 404 default
ErrorDocument 500 default
 
<IfModule mod_rewrite.c>
    RewriteEngine On
 
    #    If you are having problems with the rewrite rules, remove the "#" from the
    #    line that begins "RewriteBase" below. You will also have to change the path
    #    of the rewrite to reflect the path to your XenForo installation.
    #RewriteBase /xenforo
 
    #    This line may be needed to enable WebDAV editing with PHP as a CGI.
    #RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
 
    RewriteCond %{REQUEST_FILENAME} -f [OR]
    RewriteCond %{REQUEST_FILENAME} -l [OR]
    RewriteCond %{REQUEST_FILENAME} -d
    RewriteRule ^.*$ - [NC,L]
    RewriteRule ^(data/|js/|styles/|install/|favicon\.ico|crossdomain\.xml|robots\.txt) - [NC,L]
    RewriteRule ^.*$ index.php [NC,L]
</IfModule>

And here is the code I need to include,

Code:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /db/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /db/index.php [L]
</IfModule>

So, what will be my total code then?

If I go to this link,
http://joubonjatra.com/db/hello-world/
Its showing me error.

Never mind, problem solved.