Before updating scaffolding from new db schema try creating
(Remember that you need to refresh the file list in Eclipse to see the files you just generated).
Once, you have started Eclipse, open the file method is applied when moving down a version number (from version 1 to 0).
In this section, we're going to develop a series of migrations to recreate the database structure outlined in Chapter 2 of the book Ruby on Rails Enterprise Application Development: Plan, Program, Extend.
First, we'll work on a model and migration for the $ ruby script/generate model Person exists app/models/ exists test/unit/ exists test/fixtures/ create app/models/create test/unit/person_create test/fixtures/exists db/migrate create db/migrate/001_create_people.rb).
However, migrations don't work with every database adapter in Rails: check the Database Support section of the documentation to find out whether your adapter is supported.
At the time of writing, My SQL, Postgre SQL, SQLite, SQL Server, Sybase, and Oracle were all supported by migrations.
Active Record is the ORM layer (see the section Connecting Rails to a Database in the previous article) used in Rails.
The actual database table will be generated from a migration attached to the model.
A team of developers can use migrations to keep their databases in sync: when a change to the database is made by one of the team and coded into a migration, the other developers can apply the same migration to their database, so they are all working with a consistent structure.
When you run a migration, the Ruby script is converted into the SQL code appropriate to your database server and executed over the database connection.
Each model will usually correspond to a table in the database.
The name of the database table is, by convention, the pluralized (in the English language), lower-case form of the model's class name.