update wp_options set option_value = REPLACE(option_value,'www.old_site.com','www.new_site.com');
update wp_postmeta set meta_value = REPLACE(meta_value,'www.old_site.com','www.new_site.com');
update wp_posts set guid = REPLACE(guid,'www.old_site.com','www.new_site.com'), post_content = REPLACE(post_content,'www.old_site.com','www.new_site.com');