How To Change the Column Name and Column Type

1.How to change a column name in a migration:

Generate a migration in the console: rails g migration ChangeColumnName
Go to the generated migration file and modify the change method in this way: rename_column :table_name, :old_column, :new_column
class ChangeColumnName < ActiveRecord::Migration[5.0]
def change
rename_column :users, :email, :email_address
end
end
Run rails db:migrate, and don’t forget to update your code with the new name NOTICE:
Be careful with the reserved names in Rails or SQL when you rename a columnSomething to look out when you rename a column in Rails: the reserved names. You will run into troubles if you use them, sometimes not right away.
And there are a LOT of them. Therefore, you can’t rename your database column using ‘group’, ‘image’, ‘set’, ‘open’, etc.

2.How to change a Column Type in a migration:
Generate a migration in the console: rails g migration ChangeColumnName
Go to the generated migration file and modify the change method in this way: rename_column :table_name, :table_name, :new_type
Run rails db:migrate, and don’t forget to update your code with the new name
class ChangeDateColumnToDatetime < ActiveRecord::Migration[5.0]
def up
change_column :projects, :deadline, :datetime
end
def down
change_column :projects, :deadline, :date
end
.