-- 专门查询的sql
select *
from tb_news;

select *
from tb_billboard;

select *
from tb_football_club;

select a.*,
  b.*,
  c.*,
  d.*
from tb_score a
  inner join tb_student b on a.stu_id = b.sid
  inner join tb_subject c on a.sub_id = c.sid
  inner join tb_class d on b.cid = d.cid;

select count(*)
from tb_joke;