Question

在此示例数据库中，有两个表，产品和价格。目标是找到每种产品的最高价和最低价。

价格表每个产品可以有零行，一行或两行。

create table products(
    id int,
    name nvarchar(50)
)

create table prices(
    productId int,
    price int
)

insert into products (id, name) values (33,'bike')
insert into products (id, name) values (44,'car')
insert into products (id, name) values (55,'bus')

insert into prices (productId, price) values (33, 10)
insert into prices (productId, price) values (33, 40)
insert into prices (productId, price) values (44, 300)

sql查询应该导致：

productId  highPrice  lowPrice
33         40         10
44         300        NULL
55         NULL       NULL

Answer 1

SELECT productId,
        MAX(price) AS highPrice,
        MIN(price) AS lowPrice
FROM prices
GROUP BY productId

如果您还想要产品名称：

SELECT name,
        MAX(price) AS highPrice,
        MIN(price) AS lowPrice
FROM products
    LEFT OUTER JOIN prices ON ID = ProductID
GROUP BY name

Answer 2

这适用于MySQL，但它也可能对你有用。

SELECT
products.id as productId
, MIN(price) as highPrice
, MAX(price) as lowPrice
FROM products
  LEFT JOIN prices ON products.id=prices.productId
GROUP BY products.id

Answer 3

这为您提供了您正在寻找的表（我注意到其他答案没有），在SQL Server 2005中

select P.ID as ProductID, 
nullif(sum(case when idx=1 then price else 0 end), 0) as highPrice,
nullif(sum(case when idx=2 then price else 0 end), 0) as lowPrice  from
(
    select productid, price, row_number() over(partition by productID order by price desc) as idx from prices
) T
right join products P on T.productID = P.ID
group by P.ID

在sql中找到高价和低价

3 个答案: