如何将表格的前两列堆叠为一列?

问题描述

我想将表的两列堆叠为一列.因此，例如，如果源表是:| Id | Code_1 | Code_2 | Other ||----|---------|---------|-------|| 1 | Value_1 | Value_2 | Row_1 || 2 | Value_3 | (null) | Row_2 || 3 | (null) | Value_4 | Row_3 || 4 | (null) | (null) | Row_4 || 5 | Value_5 | (null) | Row_5 |

I'd like to stack two columns of a table into a single column. So for example, if the source table is:| Id | Code_1 | Code_2 | Other ||----|---------|---------|-------|| 1 | Value_1 | Value_2 | Row_1 || 2 | Value_3 | (null) | Row_2 || 3 | (null) | Value_4 | Row_3 || 4 | (null) | (null) | Row_4 || 5 | Value_5 | (null) | Row_5 |

然后目标表应为:| Id | Code | Other ||----|---------|-------|| 1 | Value_1 | Row_1 || 2 | Value_2 | Row_1 || 3 | Value_3 | Row_2 || 4 | Value_4 | Row_3 || 5 | Value_5 | Row_5 |

Then the target table should be:| Id | Code | Other ||----|---------|-------|| 1 | Value_1 | Row_1 || 2 | Value_2 | Row_1 || 3 | Value_3 | Row_2 || 4 | Value_4 | Row_3 || 5 | Value_5 | Row_5 |

请注意，Other列仅重复其值，但仅当Code_1和Code_2中存在非空值时.

Notice that the Other column just duplicates its values, but only when there's a non-null value in Code_1 and Code_2.

我试图使用PIVOT语句cos，我本质上是试图(几乎)堆叠每一行的转置，但是我不知道如何正确地对其进行编排.

I tried to use a PIVOT statement cos I'm essentially trying to (almost) stack transposes of each row, but I can't figure out how to orchestrate it properly.

我的DDL在下面:

CREATE TABLE Source ( Id INT IDENTITY(1, 1) PRIMARY KEY, Code_1 VARCHAR(10), Code_2 VARCHAR(10), Other VARCHAR(10));INSERT INTO Source VALUES ('Value_1', 'Value_2', 'Row_1'), ('Value_3', NULL, 'Row_2'), (NULL, 'Value_4', 'Row_3'), (NULL, NULL, 'Row_4'), ('Value_5', NULL, 'Row_5');

CREATE TABLE Source ( Id INT IDENTITY(1, 1) PRIMARY KEY, Code_1 VARCHAR(10), Code_2 VARCHAR(10), Other VARCHAR(10));INSERT INTO Source VALUES ('Value_1', 'Value_2', 'Row_1'), ('Value_3', NULL, 'Row_2'), (NULL, 'Value_4', 'Row_3'), (NULL, NULL, 'Row_4'), ('Value_5', NULL, 'Row_5');

CREATE TABLE Target ( Id INT IDENTITY(1, 1) PRIMARY KEY, Code VARCHAR(10), Other VARCHAR(10));INSERT INTO Target VALUES ('Value_1', 'Row_1'), ('Value_2', 'Row_1'), ('Value_3', 'Row_2'), ('Value_4', 'Row_3'), ('Value_5', 'Row_5')

CREATE TABLE Target ( Id INT IDENTITY(1, 1) PRIMARY KEY, Code VARCHAR(10), Other VARCHAR(10));INSERT INTO Target VALUES ('Value_1', 'Row_1'), ('Value_2', 'Row_1'), ('Value_3', 'Row_2'), ('Value_4', 'Row_3'), ('Value_5', 'Row_5')

推荐答案

您需要unpivot:

SELECT Id, Code, Other
FROM
   Source
UNPIVOT
   (Code FOR code_ IN
      (code_1, code_2)
) AS unpvt;

请参见在此处进行小提琴.

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