```ruby
class CreateShifts < ActiveRecord::Migration[5.0]
  def change
    create_table :shifts do |t|
      t.belongs_to :event, index: true
      t.datetime :starts_at
      t.datetime :ends_at
      t.integer :volunteers_needed
      t.integer :volunteers_count

      t.timestamps
    end
  end
end
```

Set volunteer count field's default to 0
user
```ruby
class CreateShifts < ActiveRecord::Migration[5.0]
  def change
    create_table :shifts do |t|
      t.belongs_to :event, index: true
      t.datetime :starts_at
      t.datetime :ends_at
      t.integer :volunteers_needed
      t.integer :volunteers_count, default: 0

      t.timestamps
    end
  end
end
```
assistant