MySQL:如何转换为 EAV？

Question

假设我有下表:

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

我想将其转换为 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 one.id
• two.attribute 值来自 one.first_name
• two.value 值来自 one.last_name

我需要从表 1 创建表 2，以便运行一些测试。

Answer 1

我假设 two.id 是一个自动递增的整数，所以我将把它留给目标表来分配这些值。

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