MySQL：如何转换为EAV？

问题描述

我有以下表格：

TABLE: one
===============================
| id | first_name | last_name |
===============================
| 1  | John       | Doe       |
| 2  | Jane       | Smith     |
-------------------------------

我想将它转换为EAV：

I want to convert it to an EAV:

TABLE: two
===================================
| id | fk_id | attribute  | value |
===================================
| 1  | 1     | first_name | John  |
| 2  | 1     | last_name  | Doe   |
| 3  | 2     | first_name | Jane  |
| 4  | 2     | last_name  | Smith |
-----------------------------------

注意：

• two.fk_id值来自一个。 id


• two.attribute值来自one.first_name


• two.value值来自one.last_name

我需要从表一创建表二，所以我可以运行一些测试。

I need to create table two from table one so I can run some tests.

推荐答案

我假设two.id是一个自动递增的整数，所以我将它留给目标表来分配这些值。

I'm assuming two.id is an autoincrementing integer, so I'll leave it to the target table to assign those values.

select id as fk_id, 'first_name' as attribute, first_name as value
from one
union all
select id as fk_id, 'last_name', last_name
from one
order by fk_id, attribute

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