TAGS:

ruby  rails  migration  database  add 

Related:

• Adding fields to table via migration.
• Creating migration file using generate migration
• Creation migration file using generate model.
• Creating migration file using scaffold.
• Drop tables using migration.
• Editing migration file manually.</li>
• Seeding data into tables via migration.
• Joining two tables via migration.
• Migration specific VERSION or STEP.
• Setting rails environment via migration command.
• Setup, reset and drop database
</ul>


Removing Fields From Table Via Rails Migration.

First, We suppose that you have a `books` table as:

rails g scaffold book name brief:text price:float
rake db:migrate

Now, You can remove the column `price` using:

rails g migration RemovePriceFromBooks price:float

This mean, Remove price field from the books table, and will create a migration file as:

class RemovePriceFromBooks<ActiveRecord::Migration
	def change
		remove_column :books, :price, :float
	end 
end

Then run

rake db:migrate

This will remove the `price` column form `books` table. Take care, The data stored in this field will be destoyed and can't be restored, So, What will happened if you run:

rake db:rollback

Sure, It will restore `price` field but not restore its `data`.