Question

我有两个Mysql表：

products，ID，姓名，链接
products-prices包含id，id_prod，价格，可用性和日期

在第二个中，正如您所看到的，我可以根据更新的时间为同一产品提供更多价格，我想要做的是让一个查询向我展示最低价格，平均价格和最新价格价钱。我可以在一个查询中获得前两个（最低和平均价格）和另一个查询中的最新价格，但我不知道如何连接它们或者是否有其他方式。

我的第一个查询如下：

SELECT 
    `products`.id AS ids, `products`.name, `products`.link, 
    `products-prices`.id AS id_p, `products-prices`.price, 
    `products-prices`.availability, `products-prices`.date, 
    AVG(`products-prices`.price) AS medie, 
    MIN(`products-prices`.price) AS minim 
FROM
    `products-prices` 
INNER JOIN 
    `products` ON `products`.id = `products-prices`.id_produs 
GROUP BY 
    ids 
ORDER BY 
    ids

，第二个是：

SELECT * 
FROM `products-prices`
WHERE date IN (SELECT DISTINCT MAX(date) max_date 
               FROM `products-prices` 
               GROUP BY id_produs)

你能告诉我如何将它们结合起来吗？非常感谢你！

（我不知道UNION是如何工作的，如果有效，我会试试）

//编辑：我还有另外一个问题，我可以在数据库中没有最新条目的情况下获取MIN，AVG值吗？

Answer 1

您可以使用子选择作为最大日期

  select 
      `products`.id AS ids, 
      `products`.name, 
      `products`.link,
      t.date,
      t.price,
      t.availability,
       AVG(`products-prices`.price) AS medie, 
       MIN(`products-prices`.price) AS minim 

  from  `products`
  inner join `products-prices`  ON `products`.id=`products-prices`.id_produs 
  inner join ( )
  select id_produs, date, price, availability
  from `products-prices` 
  where ( id_produs, date ) = (
  select id_produs, max(date) as max_date
  from `products-prices` 
  group by id ) t on t.id_produs = `products`.id_prod

Answer 2

这是一个未经测试的解决方案，如果有帮助请告诉我

SELECT 
    `products`.id AS ids, `products`.name, `products`.link, 
    `products-prices`.id AS id_p, `products-prices`.price, 
    `products-prices`.availability, `products-prices`.date, 
    AVG(`products-prices`.price) AS medie, 
    MIN(`products-prices`.price) AS minim,
    latest.`date` as latest_date,
    latest.price as latest_price 
FROM
    `products-prices` 
INNER JOIN 
    `products` ON `products`.id = `products-prices`.id_produs 
INNER JOIN
    (select id_produs, price, `date` 
     from `products-prices` t1
     where not exists (select 1
                       from `products-prices` t2
                       where t1.`date` < t2.`date` and t1.id_produs = t2.id_produs)
     group by id_produs
    ) latest     
ON
    latest.id_produs = products.id
GROUP BY 
    ids 
ORDER BY 
    ids

Mysql从两个表（产品和产品价格）获得min，avg和latest

2 个答案: