SQL 当列数据位于具有鉴别器列的单列中时进行数据透视

Question

我有一组数据代表人们如何对各种特征进行排名。我正在尝试按两列对数据进行透视，但是，列数据包含在一个单独的列下，其中一个单独的列充当鉴别器。

这是场景。人们得到了一份包含三个特征的清单，并要求他们按照对他们的重要性进行排序。他们得到了两份清单，每份清单包含三个特征，并要求他们按照从最重要到最不重要的顺序对每个清单进行 1 到 3 的排序。

+----------+-------+----------------+---------------+------+
| RecordNo |  Name | QuestionNumber | QuestionGroup | Rank |
+----------+-------+----------------+---------------+------+
|     1    |  Bob  |        1       |       1       |   2  |
|     2    |  Bob  |        2       |       1       |   1  |
|     3    |  Bob  |        3       |       1       |   3  |
|     4    |  Bob  |        1       |       2       |   1  |
|     5    |  Bob  |        2       |       2       |   2  |
|     6    |  Bob  |        3       |       2       |   3  |
|     7    | Sally |        1       |       1       |   3  |
|     8    | Sally |        2       |       1       |   2  |
|     9    | Sally |        3       |       1       |   1  |
|    10    | Sally |        1       |       2       |   1  |
|    11    | Sally |        2       |       2       |   3  |
|    12    | Sally |        3       |       2       |   2  |
+----------+-------+----------------+---------------+------+

我想得到的是数据的 PIVOT，所以它看起来像这样..

+----------+-------+-----------+-----------+-----------+------------+------------+------------+
| RecordNo |  Name | Question1 | Question2 | Question3 | Question 1 | Question 2 | Question 3 |
|          |       |  Group 1  |  Group 1  |  Group 1  |   Group 2  |   Group 2  |   Group 2  |
+----------+-------+-----------+-----------+-----------+------------+------------+------------+
|     1    |  Bob  |     2     |     1     |     3     |      1     |      2     |      3     |
|     2    | Sally |     3     |     2     |     1     |      1     |      3     |      2     |
+----------+-------+-----------+-----------+-----------+------------+------------+------------+

我知道如何在多个列上进行数据透视 great article on it here 但我无法弄清楚的是当数据位于由鉴别器列 (QuestionGroup) 分隔的同一列 (QuestionNumber) 中时如何进行数据透视。

我还在线创建了一个tablehere

Answer 1

我认为最简单的数据透视方法是条件聚合：

select name,
       max(case when questiongroup = 1 and questionnumber = 1 then rank end) as q_1_1,
       max(case when questiongroup = 1 and questionnumber = 2 then rank end) as q_1_2,
       max(case when questiongroup = 1 and questionnumber = 3 then rank end) as q_1_3,
       max(case when questiongroup = 2 and questionnumber = 1 then rank end) as q_2_1,
       max(case when questiongroup = 2 and questionnumber = 2 then rank end) as q_2_2,
       max(case when questiongroup = 2 and questionnumber = 3 then rank end) as q_2_3
from t
group by name;

SQL 当列数据位于具有鉴别器列的单列中时进行数据透视

SQL Pivot when column data is in single column with a discriminator column

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