如何将db中的数据从字符串更改为id-Rails,Mysql

您好我可能有一个简单的问题,也许不是…

历史记录：我想用状态替换为db(mysql)的yaml文件,并且我在用户表列中有：status.当我将逻辑替换为db时,我已经创建了模型状态,创建了表并配置了与用户的关系…

描述问题：当我在用户表中创建status_id时,我有2列：“ status”和“ status_id”. “状态”列是字符串,并且具有很多字符串值,例如“已确认”.如何(使用带有状态的种子迁移)并填写“ status_id”列.我的意思是,如果“ status”列的值是“ confirmed”,我想在“ status_id”列的值中包含：1.

statuses table:
id name
1   confirmed
2   not confirmed
3   something else


Users table
id status           status_id
1  confirmed        empty
2  confirmed        empty
3  confirmed        empty
4  not confirmed    empty
5  not confirmed    empty
6  something else   empty
7  something else   empty

User belongs_to :status

Status has_many :users

question: Why i didnt just change name and type in “status” column on
“status_id” with data type: “id”?

answer: Because i need to deploy it using capistrano to production
server and i cant losing data and remove data from status column.

解决方法:

给定以下(您的)样本数据：

create table statuses (id int, name char(20));
insert into statuses (id, name) values
    (1, 'confirmed'),
    (2, 'not confirmed'),
    (3, 'something else');

create table users (id int, status char(20), status_id int);
insert into users (id, status) values
    (1,'confirmed'),
    (2,'confirmed'),
    (3,'confirmed'),
    (4,'not confirmed'),
    (5,'not confirmed'),
    (6,'something else'),
    (7,'something else');

select * from users;
+------+----------------+-----------+
| id   | status         | status_id |
+------+----------------+-----------+
|    1 | confirmed      |      NULL |
|    2 | confirmed      |      NULL |
|    3 | confirmed      |      NULL |
|    4 | not confirmed  |      NULL |
|    5 | not confirmed  |      NULL |
|    6 | something else |      NULL |
|    7 | something else |      NULL |
+------+----------------+-----------+
7 rows in set (0.00 sec)

此更新语句使用状态中的适当值更新用户中的status_id列：

update users u 
   set u.status_id=(select s.id from statuses s where u.status=s.name);
Query OK, 7 rows affected (0.01 sec)
Rows matched: 7  Changed: 7  Warnings: 0

select * from users;
+------+----------------+-----------+
| id   | status         | status_id |
+------+----------------+-----------+
|    1 | confirmed      |         1 |
|    2 | confirmed      |         1 |
|    3 | confirmed      |         1 |
|    4 | not confirmed  |         2 |
|    5 | not confirmed  |         2 |
|    6 | something else |         3 |
|    7 | something else |         3 |
+------+----------------+-----------+
7 rows in set (0.00 sec)

希望这是您所要的,因为我的回答不涉及ruby,yaml或滑轨.

标签：yaml,rails-migrations,ruby-on-rails,mysql,database
来源： https://codeday.me/bug/20191118/2030335.html