Question

我想把两个问题放在一起;一个来自我的posts表，一个来自我的store_products表，并在同一页面上显示结果。

所以我想接受这个...

SELECT 
      p.id AS pid 
    , p.uid
    , p.title
    , p.created_at
    , u.id AS uid
    , u.username
    , u.avatar 
    , f.following 
    , l.uid AS liked
    , u2.username AS source_username
    , u2.avatar AS source_avatar
    , u2.created_at AS source_created_at
FROM posts p 
LEFT JOIN users u ON p.uid=u.id 
LEFT JOIN posts_likes l ON l.pid=p.id 
LEFT JOIN follow f ON u.id = f.following 
LEFT JOIN posts p2 ON p.source_hash = p2.hash 
LEFT JOIN users u2 ON u2.id = p2.uid 
WHERE (f.user=2 OR p.uid=2) 
GROUP BY p.id ORDER BY p.id DESC

并用这样的东西......

SELECT name, price FROM store_products WHERE uid=2

我尝试了多个SELECT语句，UNION，我使用NULL弥补了cols的差异，我尝试了LEFT，{ {1}}和RIGHT加入，但所有这些都是将产品信息添加到其他帖子行，而不是为每个产品创建单独的行。

我正在寻找的结果集类似于

INNER

等...

编辑：回答问题。两个表之间的唯一关系是用户ID，否则它们是完全分开的。我想向访问者提供帖子和产品的列表，我试图在一个查询中执行此操作以节省服务器负载，并将它们放在同一列表中而不是单独的列表中。

Answer 1

使用UNION：

SELECT 
      "Post" AS type,
    , p.id AS pid 
    , p.uid
    , p.title
    , p.created_at
    , u.id AS uid
    , u.username
    , u.avatar 
    , f.following 
    , l.uid AS liked
    , u2.username AS source_username
    , u2.avatar AS source_avatar
    , u2.created_at AS source_created_at
    , NULL AS product_name
    , NULL AS price
FROM posts p 
LEFT JOIN users u ON p.uid=u.id 
LEFT JOIN posts_likes l ON l.pid=p.id 
LEFT JOIN follow f ON u.id = f.following 
LEFT JOIN posts p2 ON p.source_hash = p2.hash 
LEFT JOIN users u2 ON u2.id = p2.uid 
WHERE (f.user=2 OR p.uid=2) 
GROUP BY p.id 
ORDER BY p.id DESC

UNION

SELECT 
      "Product" AS type
    , NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
    , name, price
FROM store_products
WHERE uid = 2

然后，应用程序代码可以检查type列，以确定它是否正在打印Post或Product，并对其进行适当格式化。

mySQL Multiple SELECT：1复杂1简单

1 个答案: