code: def update_count(cat_id):
          '''
          Update the count of certain category.
          '''
          # Todo: the record not valid should not be counted.
          entry2 = TabTag.update(
              count=TabPost2Tag.select().where(
                  TabPost2Tag.tag_id == cat_id
              ).count()
          ).where(TabTag.uid == cat_id)
          entry2.execute(f update_count(cat_id):
          '''
          Update the count of certain category.
          '''
          # Todo: the record not valid should not be counted.
          entry2 = TabTag.update(
              count=TabPost2Tag.select().where(
                  TabPost2Tag.tag_id == cat_id
              ).count()
          ).where(TabTag.uid == cat_id)
          entry2.execute()
docs: Update the count of certain category.