Creating migrations in Ruby on Rails - Quick Revision & Summary

Recall & Review

beginner

What is a migration in Rails?

A migration is a way to change the database schema over time in a consistent and easy way. It helps create, modify, or drop tables and columns.

beginner

How do you generate a new migration file in Rails?

Use the command rails generate migration MigrationName. This creates a new migration file with a timestamp.

beginner

What method do you use inside a migration to create a new table?

Use the create_table method inside the change method to define a new table and its columns.

intermediate

What does the change method do in a migration?

The change method defines the changes to apply to the database. Rails can automatically reverse these changes when rolling back.

beginner

How do you run migrations to update the database schema?

Run rails db:migrate to apply all pending migrations and update the database schema.

Which command creates a new migration file in Rails?

A rails migration create AddUserEmail

B rails generate migration AddUserEmail

C rails new migration AddUserEmail

D rails create migration AddUserEmail

The correct command is rails generate migration MigrationName to create a new migration file.

What method inside a migration defines the database changes?

A change

B update

C modify

D alter

The change method defines the changes to apply in the migration.

How do you apply migrations to update the database?

A rails db:migrate

B rails db:reset

C rails db:rollback

D rails db:create

Use rails db:migrate to apply migrations and update the database schema.

Which method creates a new table in a migration?

A make_table

B add_table

C new_table

D create_table

The create_table method is used to create a new table inside a migration.

What does Rails use to order migration files?

A Alphabetical order

B File size

C Timestamp in filename

D Random order

Rails orders migrations by the timestamp prefix in the filename to run them in the correct sequence.

Explain how to create and run a migration to add a new column to an existing table in Rails.

Think about the command to create migration, the method to add a column, and how to apply it.

Describe the purpose of the change method in Rails migrations and how it helps with rolling back changes.

Focus on how change method works both forward and backward.