Multisite Problem Example

gistfile1.php

if ( is_admin() ) {
	$this->install(is_multisite() ? true : false);	//we run this here because activation hooks aren't triggered when updating - see http://wp.mu/8kv
	$this->init_admin_pages();
}

gistfile2.php

	function install( $network_activate ) {
		global $wpdb;

		// Move wiki_version option from blog table to sitemeta table
		if ( $wiki_version = get_option('wiki_version') ) {
			update_site_option('wiki_version', $wiki_version);
			delete_option('wiki_version');
		}

		if ( get_site_option('wiki_version', false) == $this->version )
			return;

		// WordPress database upgrade/creation functions
		require_once ABSPATH . 'wp-admin/includes/upgrade.php';

		// Get the correct character collate
		$charset_collate = '';
		if ( ! empty($wpdb->charset) )
			$charset_collate .= "DEFAULT CHARSET $wpdb->charset";
		if ( ! empty($wpdb->collate) )
			$charset_collate .= " COLLATE $wpdb->collate";

		// Setup the subscription table
		dbDelta("
			CREATE TABLE {$this->db_prefix}wiki_subscriptions (
				ID BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
				blog_id BIGINT(20) NOT NULL,
				wiki_id BIGINT(20) NOT NULL,
				user_id BIGINT(20),
				email VARCHAR(255),
				PRIMARY KEY  (ID)
			) ENGINE=InnoDB $charset_collate;");

		// Setup blog(s)
		if ( $network_activate ) {
			$results = $wpdb->get_results("
				SELECT blog_id
				FROM $wpdb->blogs
			");

			foreach ( $results as $row ) {
				$this->setup_blog($row->blog_id);
			}
		} else {
			$this->setup_blog();
		}

		update_site_option('wiki_version', $this->version);
	}