1 => 4
8 => 23
15 => 9

UPDATE wp_posts
SET post_author = '4'
WHERE post_author = '1'

RENAME TABLE `wp_posts`
TO `tenp_15_posts`;

define( 'DOMAIN_CURRENT_SITE', 'www.your-domain.com' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );