將列轉換為 SQL Server 中的行？

Question

我有以下銷售表（SQL Server 2017）（每個商品大約有 20 行）：

+---------+----------+-------------+-------+---------+------+
| good_id | store_id | week_number | promo | holiday | sale |
+---------+----------+-------------+-------+---------+------+
| 201712  | 255      | 1           | 1     | 0       | 2    |
+---------+----------+-------------+-------+---------+------+
| 201712  | 255      | 2           | 0     | 0       | 0    |
+---------+----------+-------------+-------+---------+------+

我想准備一個數據集，以便特定商店中的每種商品對應一行：

+---------+----------+---------------+---------------+---------+---------+-----------+-----------+--------+--------+
| good_id | store_id | week_number_1 | week_number_2 | promo_1 | promo_2 | holiday_1 | holiday_2 | sale_1 | sale_2 |
+---------+----------+---------------+---------------+---------+---------+-----------+-----------+--------+--------+
| 201712  | 255      | 1             | 2             | 1       | 0       | 0         | 0         | 2      | 0      |
+---------+----------+---------------+---------------+---------+---------+-----------+-----------+--------+--------+

我知道如何為具有唯一值的單列執行此操作：

SELECT *
FROM
(
    SELECT [good_id],
           [store_id],
           [week_number],
           [sale]
    FROM table
    WHERE good_id = 201712
    AND store_id = 255
) AS SourceTable PIVOT(AVG([sale]) FOR [week_number] IN([1],
                                                         [2])) AS PivotTable

但是我要怎么寫我需要的代碼，我還看不懂

Answer 1

您可以使用條件聚合：

select good_id, store_id,
       max(case when week_number = 1 then promo end) as promo_1,
       max(case when week_number = 1 then holiday end) as holiday_1,
       max(case when week_number = 1 then sale end) as sale_1,
       max(case when week_number = 2 then promo end) as promo_2,
       max(case when week_number = 2 then holiday end) as holiday_2,
       max(case when week_number = 2 then sale end) as sale_2,
       . . . 
from table
group by good_id, store_id;