wpdb::get_blog_prefix PHP Method

    public function get_blog_prefix($blog_id = null)
    {
        if (is_multisite()) {
            if (null === $blog_id) {
                $blog_id = $this->blogid;
            }
            $blog_id = (int) $blog_id;
            if (defined('MULTISITE') && (0 == $blog_id || 1 == $blog_id)) {
                return $this->base_prefix;
            } else {
                return $this->base_prefix . $blog_id . '_';
            }
        } else {
            return $this->base_prefix;
        }
    }

 /**
  * Reinitialize the object
  *
  * Recreates the role objects. This is typically called only by switch_to_blog()
  * after switching wpdb to a new site ID.
  *
  * @since 3.5.0
  * @access public
  */
 public function reinit()
 {
     // There is no need to reinit if using the wp_user_roles global.
     if (!$this->use_db) {
         return;
     }
     // Duplicated from _init() to avoid an extra function call.
     $this->role_key = $this->db->get_blog_prefix() . 'user_roles';
     $this->roles = get_option($this->role_key);
     if (empty($this->roles)) {
         return;
     }
     $this->role_objects = array();
     $this->role_names = array();
     foreach (array_keys($this->roles) as $role) {
         $this->role_objects[$role] = new WP_Role($role, $this->roles[$role]['capabilities']);
         $this->role_names[$role] = $this->roles[$role]['name'];
     }
 }