Question

我已尝试过db:setup db:rollback db:drop db:migrate VERSION="0"几乎我能想到的一切，但我无法弄清楚这个错误。我甚至尝试在初始化create方法之前运行它并删除表。即使我创建了一个新产品，就像产品数据库一样，它告诉我它在那里，但它告诉我，当我试图放弃它时它不存在。我花了两天时间浏览论坛和视频，找出发生了什么。这种情况发生在sqlite和mysql上。

- 已修改为包含迁移类 -

class CreateTablenames < ActiveRecord::Migration
  def change
    create_table :tablenames do |t|
      t.string :ID
      t.string :col1
      t.string :col2
      t.string :col3

      t.timestamps null: false
    end
  end
end

- 结束编辑

E:\RailsApplications\Blog>rake db:migrate
== 20151130191336 CreateTablenames: migrating =================================
-- create_table(:tablenames)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: duplicate column name: ID: CREATE TABLE "tablenames" ("id
" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "ID" varchar, "col1" varchar, "col
2" varchar, "col3" varchar, "created_at" datetime NOT NULL, "updated_at" datetim
e NOT NULL) E:/RailsApplications/Blog/db/migrate/20151130191336_create_tablename
s.rb:3:in `change'
C:in `migrate'
ActiveRecord::StatementInvalid: SQLite3::SQLException: duplicate column name: ID
: CREATE TABLE "tablenames" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "I
D" varchar, "col1" varchar, "col2" varchar, "col3" varchar, "created_at" datetim
e NOT NULL, "updated_at" datetime NOT NULL)
E:/RailsApplications/Blog/db/migrate/20151130191336_create_tablenames.rb:3:in `c
hange'
C:in `migrate'
SQLite3::SQLException: duplicate column name: ID
E:/RailsApplications/Blog/db/migrate/20151130191336_create_tablenames.rb:3:in `c
hange'
C:in `migrate'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

E:\RailsApplications\Blog>rake db:migrate
== 20151130191336 CreateTablenames: migrating =================================
-- drop_table(:tablenames)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: no such table: tablenames: DROP TABLE "tablenames"E:/Rail
sApplications/Blog/db/migrate/20151130191336_create_tablenames.rb:3:in `change'
C:in `migrate'
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such table: tablenames
: DROP TABLE "tablenames"
E:/RailsApplications/Blog/db/migrate/20151130191336_create_tablenames.rb:3:in `c
hange'
C:in `migrate'
SQLite3::SQLException: no such table: tablenames
E:/RailsApplications/Blog/db/migrate/20151130191336_create_tablenames.rb:3:in `c
hange'
C:in `migrate'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

Answer 1

您正在尝试创建一个包含两列名为id的表：

ActiveRecord::StatementInvalid: SQLite3::SQLException: duplicate column name: ID : CREATE TABLE "tablenames" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "I D" varchar, ...

默认情况下，我们已为rails创建了id，然后您尝试添加ID类型的另一个varchar。

您需要将ID重命名为其他内容，或者您需要告诉rails不要创建其id列：

create table :tablenames, id: false do |t|
  t.string :ID
  ... rest of your migration
end

理想情况下，只需删除重复的ID列并让Rails完成它。

rake db：migrate问题重复，但不存在

1 个答案: