如何计算SQL中的出现次数

Question

我有一个清单（例如衬衫、上衣、裤子、阿迪达斯、耐克、彪马等）和年份，格式如下 2017-01-01。 我想知道每件商品每年购买的次数并按年份排列。

我怎样才能做到这一点？

我有下表称为项目：

Year | Purchases | 
------------------
2017-01-01 | makeup
2018-01-01 | clothing
2019-01-01 | makeup
2017-01-01 | shoes
2017-01-01 | clothing
2016-01-01 | shoes
2018-01-01 | clothing
2017-01-01 | clothing
2019-01-01 | makeup

所需的输出是这样的：

Year | Purchases| Count
-----------------------
2016 | Shoes    |  1
2017 | Makeup   |  1
2017 | Clothing |  2
2017 | Shoes    |  1
2018 | Clothing |  2
2019 | Makeup   |  2

到目前为止，我的代码是这样的：

SELECT YEAR(d.date_format) AS Year
      , Purchase = (CASE WHEN it.type IN ('shirts', 'tops', 'pants) THEN 'clothing'
                     WHEN it.type('nike','adidas', 'puma') THEN 'shoes'
                     WHEN it.type('facewash', 'lipstick') THEN 'makeup' END), COUNT(*)
FROM ....
    INNER JOIN...
WHERE...
GROUP BY Year, Purchase
ORDER BY Year

Answer 1

select year, purchases, count(*)
from table
group by year, purchase
order by 1, 2

Answer 2

您可以使用group by和order by

select year, purchases, count(*) 
from myTable
group by year, purchases
order by year

Answer 3

这是你想要的吗？

SELECT YEAR(d.date_format) AS Year,
       (CASE WHEN it.type IN ('shirts', 'tops', 'pants') THEN 'clothing'
             WHEN it.type IN ('nike','adidas', 'puma') THEN 'shoes'
             WHEN it.type IN ('facewash', 'lipstick') THEN 'makeup'
        END), COUNT(*)
FROM .... INNER JOIN...
WHERE...
GROUP BY YEAR(d.date_format),
         (CASE WHEN it.type IN ('shirts', 'tops', 'pants') THEN 'clothing'
               WHEN it.type IN ('nike','adidas', 'puma') THEN 'shoes'
               WHEN it.type IN ('facewash', 'lipstick') THEN 'makeup'
          END)
ORDER BY Year;

在SELECT使用=表明您正在使用 SQL Server。 SQL Server 不支持在GROUP BY使用别名，因此您需要重复该表达式。