如何通过使用 join 2 次或更多次 select 随机 2 行

Question

我有 3 个 table：

  News      |      Categories      |      News_in_cat
   id       |          id          |          id
  title     |         name         |        news_id
            |                      |        cat_id

目标是从类别 table 中创建 mySql select 1 个随机类别，然后在 News_in_cat table 中查找 return 2 条随机新闻，来自 selected 类别，来自新闻 table。

Answer 1

SELECT * FROM News_in_cat AS nic
(SELECT * FROM categories ORDER BY RAND() limit 1) AS t
ON t.id = nic.cat_id
INNER JOIN News AS n 
ON n.id = nic.news_id
ORDER BY RAND()
LIMIT 2;