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Hey.

You can find instructions on creating a child theme here: http://codex.wordpress.org/Child_Themes

no need to create a folder in database.

But i don’t want to create a folder in my database

I’m not entirely sure what you mean by this sorry. You don’t have to touch your site’s database in order to create a child theme. You do, however, have to create another folder in the “themes” directory. All the info you need on this can be found here:
http://codex.wordpress.org/Child_Themes

Plus i am using a multi-site but will it effect it?

Nope, child themes work the same on multi-site installations. 🙂