Migrations methods:
- add_column
- add_index
- change_column
- change_table
- create_table
- drop_table
- remove_column
- remove_index
- rename_column
Basic format
YYYYMMDDHHMMSS_create_products.rb
Supported types
- :binary
- :boolean
- :date
- :datetime
- :decimal
- :float
- :integer
- :primary_key
- :string
- :text
- :time
- :timestamp especial type:
- :references
create_table
Commands to create migrations
$ rails generate model Product name:string description:text
$ rails generate migration AddPartNumberToProducts part_number:string
$ rails generate migration RemovePartNumberFromProducts part_number:string
$ rails generate migration AddDetailsToProducts part_number:string price:decimal
change_table
- add_column
- add_index
- add_timestamps
- create_table
- remove_timestamps
- rename_column
- rename_index
- rename_table
Running Migrations
$ rake db:migrate VERSION=20080906120000
$ rake db:rollback
$ rake db:rollback STEP=3
$ rake db:migrate:redo STEP=3
$ rake db:reset #drop database and recreate it
$ rake db:migrate:up VERSION=20080906120000
Migrations commands
rake db:migrate # Migrate the database (options: VERSION=x, VERBOSE=false).
rake db:migrate:status # Display status of migrations
rake db:rollback # Rolls the schema back to the previous version (specify steps w/ STEP=n).
rake db:test:prepare # Rebuild it from scratch according to the specs defined in the development database
more Database commands (rake -T db)
rake db:create # Create the database from config/database.yml for the current Rails.env (use db:create:all to create all dbs in t...
rake db:drop # Drops the database for the current Rails.env (use db:drop:all to drop all databases)
rake db:fixtures:load # Load fixtures into the current environment's database.
rake db:schema:dump # Create a db/schema.rb file that can be portably used against any DB supported by AR
rake db:schema:load # Load a schema.rb file into the database
rake db:seed # Load the seed data from db/seeds.rb
rake db:setup # Create the database, load the schema, and initialize with the seed data (use db:reset to also drop the db first)
rake db:structure:dump # Dump the database structure to db/structure.sql. Specify another file with DB_STRUCTURE=db/my_structure.sql
rake db:version # Retrieves the current schema version number