中止更改后出现重复列名错误
我创建了一个 Rails 数据库迁移来向数据库中的表添加一个新列，但在我注意到它花费的时间比预期长得多（15 分钟以上）后，我手动终止了运行迁移的 ruby 进程。然后我意识到，由于表中的数据量，运行时并没有异常，所以我尝试再次启动它。现在我收到错误：
Mysql::Error: Duplicate column name 'new_column': ALTER TABLE `table_name` ADD `new_column` varchar(255)
但是，当我手动进入 MySQL 时，desc table_name 显示该列不存在，并尝试手动删除它（alter table table_name drop new_column code>) 告诉我：
ERROR 1091 (42000): Can't DROP 'new_column'; check that column/key exists
看起来中止初始添加过程会导致事情进入不一致的状态。我需要做什么来解决这个问题？
编辑：我尝试手动添加（准确复制上面错误中的 DDL），然后在 MySQL 提示符下删除该列，两者都工作正常，但是 rake db:migrate继续给我上面的错误。
I created a Rails database migration to add a new column to a table in my database, but after I noticed it was taking much longer than expected (15 minutes plus), I manually killed the ruby process running the migration. Then I realized that the runtime wasn't out of the ordinary because of the amount of data in the table, so I tried started it again. Now I get the error:
Mysql::Error: Duplicate column name 'new_column': ALTER TABLE `table_name` ADD `new_column` varchar(255)
However, when I manually go into MySQL, desc table_name shows that the column doesn't exist, and trying to drop it manually (alter table table_name drop new_column) tells me:
ERROR 1091 (42000): Can't DROP 'new_column'; check that column/key exists
It looks like aborting the initial add process caused things to get into an inconsistent state. What do I need to do to resolve this?
Edit: I tried manually adding (copying exactly the DDL from the error above), then dropping the column at the MySQL prompt, and both worked fine, but rake db:migrate continues to give me the error above.
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你可以试试这个
转到此路径
并备份数据库（作为文件夹），
然后进入数据库文件夹并尝试删除表文件，
这可能有效
you can try this
go to this path
and take a backup of your database (as a folder)
then go inside the database folder and try to delete the table file
this maybe work
看起来我不小心对错误的数据库运行了手动 MySQL 命令（我没有切换到数据库的“开发”版本）。使用正确的数据库，我能够手动删除有问题的列。
It looks like I was accidentally running the manual MySQL commands against the wrong database (I wasn't switching to the "development" version of the database). Using the correct database, I was able to manually remove the offending column.