Change url multisite, no subdomain

Hello!
I installed a multisite wordpress on a domain http://www.domain.com with no subdomain, so my blogs are:
http://www.domain.com/blog1, http://www.domain.com/blog2 etc etc

Noe, I transfer my multisite wordpress on subdomain.
So, it should be on: name.domain.com
and blog on folder: name.domain.com/blog1, name.domain.com/blog2 etc etc

But I get a database connection error.
I think I should change .htaccess, but… how?

Thanks!