stevenyap/Rake Database.md

## Rake Database.md

      
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              Rake Database.md
            
          
    Create database

rake db:create
Create database table

This will creates a migration file in /db/migrate without table definition.
rails g migration create_<TABLE>
Add your table definition in the file.
class CreatePorts < ActiveRecord::Migration
  def change
    create_table :ports do |t|
      t.string :name
      t.text :description
      t.string :city
      t.string :country

      t.timestamps
    end
  end
end
Run Migrate


You need to run migration before ROR actually creates it in the database
You must run this everytime there is a new migration

rake db:migrate
Duplicate to test database


This should be ran after rake db:migrate
This duplicates your schema into the test database so that your test cases will work
Common error in test cases when you forget this step

rake db:test:prepare
Drop database

rake db:drop
Chaining commands


You can chain commands together for faster typing

rake db:drop db:create db:migration db:test:prepare
Seeding the database


Note that seeding of database should be idempotent (running it multiple times does not create duplicated records)
Add your ruby commands to add data in /db/seeds.rb like below:

puts "**  Seeding Database: seeding ***\n\n"

unless User.where(email: "admin@example.com").first
User.create!(email: 'admin@example.com',
            password: '123123',
            password_confirmation: '123123')
puts "-- Created admin@example.com with password 123123\n"
end

unless Company.where(name: "ABC").first
  Company.create!(name: "ABC")
  puts "-- Created company: ABC\n"
end

puts "\n**  Seeding Database: completed ***"
Run the command below to seed the data according to seeds.rb
rake db:seed
Roll back migration

Roll back the last migration
rake db:rollback
Or you can specify how many steps (n) to rollback. (Specify STEP=9999 to rollback everything)
rake db:rollback STEP=n
Or you can specfiy exactly the version of migration to rollback to
rake db:migrate:down VERSION=847583457438957
Or to simply rerun last migration
rake db:migrate:redo
Tip: If you are changing the latest migration, you should rake db:rollback and then add your new code to the migration file and then run rake db:migrate again
Other database commands

# View all migration logs
rake db:migrate:status