mysql - 根据聚合结果选择字段

Question

我有一个典型的products 表，其中包含字段name 和price。我必须选择所有价格的总和、最便宜产品的名称和最昂贵产品的名称，然后将其全部返回到同一结果集中。我尝试了一些组合，但我能想到的最好的方法是带有多个嵌套子选择的丑陋查询。谁能帮我提供一个好的查询示例吗？提前致谢。

为了说明问题，这里有一个简约的产品表:

+----+-------+------------------+
| id | price | name             |
+----+-------+------------------+
|  1 |  2.20 | Shack Beer       |
|  2 |  3.40 | Freeze IPA       |
|  3 |  1.10 | Poor Man's Ale   |
|  4 |  3.40 | Alabama Sour     |
|  5 |  7.20 | Irish Stout      |
+----+-------+------------------+

根据上表，查询必须返回以下结果集:

          total_pricing = 17.30
       cheapest_product = Poor Man's Ale
 most_expensive_product = Irish Stout

Answer 1

这里有几个选项供您选择 ( SQL Fiddle ):

SELECT SUM(p.price) AS total_pricing,
(
   SELECT name
   FROM products
   ORDER BY price 
   LIMIT 1
)AS cheapest_product,
(
   SELECT name
   FROM products
   ORDER BY price DESC
   LIMIT 1
)AS most_expensive_product
FROM products p;

或者在单独的行中:

SELECT 'total_pricing' as Category, SUM(p.price) AS total_pricing
FROM products p
UNION
(
  SELECT 'cheapest_product', name
  FROM products
  ORDER BY price 
  LIMIT 1
)
UNION
(
  SELECT 'most_expensive_product', name
  FROM products
  ORDER BY price DESC
  LIMIT 1
);