如何在Rails 3中创建表并拥有大量数据后重置主键(How to reset primary key after creating table and having lots data in Rai

如何在Rails 3中创建表并拥有大量数据后重置主键(How to reset primary key after creating table and having lots data in Rails 3)

如何重置主键（??）我想将我的主键设置为translate_str，让它在表中是唯一的，但我已经创建了表并在数据库中有很多日期。 我的简要代码在https://gist.github.com/poc7667/6076745谢谢你:)

How to reset primary key (??) I wanna set my primary key to translate_str , let it be unique in the table, But I've already create the table and have lots of date in the database. My Brief code is at https://gist.github.com/poc7667/6076745 Thanks you :)

最满意答案

如果您在translate_str列中有多个具有相同值的条目，那么更改表以使translate_str 唯一将给您一个错误。

如果收到错误，请删除重复记录，然后再次更改。

为了唯一性，您还可以使用Rails模型验证：

validates_uniqueness_of :translate_str

PS。 数据库中的UNIQUE属性优于validates_uniqueness_of。 如果两个请求同时由rails处理，则有时validates_uniqueness_of可能会失败。

If you have multiple entries with the same value in translate_str column, then altering your table to make translate_str unique will give you an error.

If you receive an error, remove duplicate records then do the altering again.

For uniqueness you can also use Rails model validation:

validates_uniqueness_of :translate_str

PS. UNIQUE attribute in database is better than validates_uniqueness_of. Cause validates_uniqueness_of might fail sometimes if two requests handled by rails at the same time.