Question

我需要创建一个SQL视图（使用MySQL Workbench），它应该简单地获取一行的所有值，并将它们与第一列上的各自列名称堆叠起来。像这样：

原始表：

name              | email                | address            | country    | ...
------------------|----------------------|--------------------|------------|
Al Wade Avery     | wade@hotmail.com     | 1004 Court Street  | USA        |
Antone Clay       | aclay@gmail.com      | 6219 Devon Court   | UK         |
Issac Luigi       | issac@hotmail.com    | 43 Bridge Street   | USA        |
Lucio Andrea      | lucioandrea@me.com   | 2283 Laurel Lane   | Italy      |
...               | ...                  | ...                | ...        |

查看：

field         | value             |
--------------|-------------------|
name          | Al Wade Avery     |
email         | wade@hotmail.com  |
address       | 1004 Court Street |
country       | USA               |
...           | ...               |
name          | Antone Clay       |
email         | aclay@gmail.com   |
address       | 6219 Devon Court  |
country       | UK                |
...           | ...               |
name          | Issac Luigi       |
email         | issac@hotmail.com |
address       | 43 Bridge Street  |
country       | USA               |
...           | ...               |

Answer 1

执行此操作的一种简单方法是使用union all：

create view v_table as
    select 'name' as field, name as value from t
    union all
    select 'email', email
    union all
    select 'address', address
    union all
    select 'country', country;

但是，您并不是真的想要这样做，因为您丢失了哪些字段与原始数据中的哪一行相关联的信息。如果您有一个id字段，则应在视图中包含该字段：

create view v_table as
    select id, 'name' as field, name as value from t
    union all
    select id, 'email', email
    union all
    select id, 'address', address
    union all
    select id, 'country', country;

否则，应该包括另一个唯一的列 - 可能是name。

如何创建2列SQL View？

1 个答案: