如何在不删除数据库的情况下将我的数据库迁移到第一个版本？ [英] How can I migrate my database with rails to the first revision without dropping the database first?

问题描述

我有一个数据库设置为我的Rails安装和一些迁移设置。我想能够将我的数据库重置为没有表/约束等，但是没有找到一个合理的方法来做这个，而不知道迁移的数量或第一次迁移的时间戳。这是我的选择，我看到他们：

I have a database set up for my Rails installation and some migrations set up. I would like to be able to reset my database back down to having no tables/constraints/etc., but can't find a reasonable way to do this without knowing the number of migrations or the timestamp of the first migration. Here are my options as I see them:

• rake db：migrate：reset


• rake db：migrate：down VERSION = 20090701154839 其中20090701154839是与第一次迁移相关联的时间戳记


• rake db：rollback STEP = 15 其中有15次迁移

• rake db:migrate:reset
• rake db:migrate:down VERSION=20090701154839 where 20090701154839 is the timestamp associated with the first migration
• rake db:rollback STEP=15 where there have been 15 migrations

db：migrate：reset 的问题是它首先删除数据库（它 db：drop ， db：create ，然后 db：migrate ）。

The problem with db:migrate:reset is that it drops the database first (it does db:drop, db:create, then db:migrate).

db：migrate：down 的问题是我不想对开头的VERSION进行编码。

The problem with db:migrate:down is that I don't want to encode the VERSION of the beginning.

db：rollback 的问题是我不知道回到开头的步骤数。

The problem with db:rollback is that I don't know the number of steps it is back to the beginning.

我的选项是什么？

推荐答案

rake db:migrate VERSION=0

即使您使用较新的加有时间戳记的迁移文件，它也能正常工作。

It works even if you're using the newer timestamped migration files.

更新：我刚刚在Rails 3.2.1测试这个，它仍然可以工作。它运行 schema_migrations 已知的所有迁移的下部分。我不知道它是否工作在3.1或以下，但下面的注释表明这个功能在这段时间被打破。

Update: I just tested this on Rails 3.2.1, and it still works. It runs the "down" part of all the migrations known to schema_migrations. I have no idea if it worked on 3.1 or not, but the comment below indicates that this feature was broken during that time.

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