Rails DB Migration - How To Drop a Table

Question

I added a table that I thought I was going to need  but now no longer plan on using it  How should I remove that table   I ve already run migrations  so the table is in my database  I figure rails generate migration should be able to handle this  but I haven t figured out how yet   I ve tried     rails generate migration drop tablename   but that just generated an empty migration   What is the  official  way to drop a table in Rails

User · Answer

You can roll back a migration the way it is in the guide:

http://guides.rubyonrails.org/active_record_migrations.html#reverting-previous-migrations

Generate a migration:

rails generate migration revert_create_tablename

Write the migration:

require_relative '20121212123456_create_tablename'

class RevertCreateTablename < ActiveRecord::Migration[5.0]
  def change
    revert CreateTablename    
  end
end

This way you can also rollback and can use to revert any migration

User · Answer

The simple and official way would be this     rails g migration drop tablename   Now go to your db migrate and look for your file which contains the drop tablename as the filename and edit it to this       def change       drop table  table name     end   Then you need to run      rake db migrate    on your console

User · Answer

Run  rake db migrate down VERSION  lt version gt    Where  lt version gt  is the version number of your migration file you want to revert   Example -  rake db migrate down VERSION 3846656238

User · Answer

you can simply drop a table from rails console  first open the console    rails c   then paste this command in console  ActiveRecord  Migration drop table  table name    replace table name with the table you want to delete   you can also drop table directly from the terminal  just enter in the root directory of your application and run this command    rails runner  Util  Table clobber  table name

User · Answer

Run this command -  rails g migration drop table name   then   rake db migrate   or if you are using MySql database then    login with database show databases  show tables  drop table name

User · Answer

I wasn t able to make it work with migration script so I went ahead with this solution  Enter rails console using the terminal   rails c   Type  ActiveRecord  Migration drop table  tablename    It works well for me  This will remove the previous table  Don t forget to run  rails db migrate

User · Answer

If you want to delete the table from the schema perform below operation --  rails db rollback

User · Answer

if anybody is looking for how to do it in SQL    type rails dbconsole from terminal  enter password  In console do  USE db name   DROP TABLE table name   exit  Please dont forget to remove the migration file and table structure from schema

User · Answer

First generate an empty migration with any name you d like  It s important to do it this way since it creates the appropriate date   rails generate migration DropProductsTable   This will generate a  rb file in  db migrate  like 20111015185025 drop products table rb  Now edit that file to look like this   class DropProductsTable  lt  ActiveRecord  Migration   def up     drop table  products   end    def down     raise ActiveRecord  IrreversibleMigration   end end   The only thing I added was drop table  products and raise ActiveRecord  IrreversibleMigration   Then run rake db migrate and it ll drop the table for you

User · Answer

I think  to be completely  official   you would need to create a new migration  and put drop table in self up  The self down method should then contain all the code to recreate the table in full  Presumably that code could just be taken from schema rb at the time you create the migration   It seems a little odd  to put in code to create a table you know you aren t going to need anymore  but that would keep all the migration code complete and  official   right   I just did this for a table I needed to drop  but honestly didn t test the  down  and not sure why I would

User · Answer

While the answers provided here work properly  I wanted something a bit more  straightforward   I found it here  link First enter rails console    rails console   Then just type   ActiveRecord  Migration drop table  table name    And done  worked for me

User · Answer

Alternative to raising exception or attempting to recreate a now empty table  - while still enabling migration rollback  redo etc -  def change   drop table  users  force  true  if ActiveRecord  Base connection tables include   users   end

User · Answer

ActiveRecord  Base connection drop table  table name

User · Answer

if you want to drop a specific table you can do    rails db migrate up VERSION  Here you can insert timestamp of table    otherwise if you want to drop all your database you can do   rails db drop

User · Answer

Open you rails console  ActiveRecord  Base connection execute  drop table table name

User · Answer

the best way you can do is   rails g migration Drop table Users   then  do the following  rake db migrate

User · Answer

I needed to delete our migration scripts along with the tables themselves      class Util  Table  lt  ActiveRecord  Migration   def self clobber table name           drop the table     if ActiveRecord  Base connection table exists  table name       puts   n       table name upcase cyan                      lt  lt  Time now strftime   H  M  S   yellow       drop table table name      end        locate any existing migrations for a table and delete them     base folder   File join Rails root to s   db    migrate       Dir File join base folder           rb    each do  file        if file     create   table name  rb          puts     deleting migration      file cyan                       lt  lt  Time now strftime   H  M  S   yellow         FileUtils rm rf file          break       end     end   end    def self clobber all       delete every table in the db  along with every corresponding migration      ActiveRecord  Base connection tables each   t  clobber t    end  end   from terminal window run     rails runner  Util  Table clobber  your table name     or    rails runner  Util  Table clobber all

User · Answer

You won t always be able to simply generate the migration to already have the code you want  You can create an empty migration and then populate it with the code you need   You can find information about how to accomplish different tasks in a migration here   http   api rubyonrails org classes ActiveRecord Migration html  More specifically  you can see how to drop a table using the following approach   drop table  table name

User · Answer

You need to to create a new migration file using following command  rails generate migration drop table xyz   and write drop table code in newly generated migration file  db migration xxxxxxx drop table xyz  like  drop table  tablename   Or if you wanted to drop table without migration  simply open rails console by    rails c   and execute following command  ActiveRecord  Base connection execute  drop table table name     or you can use more simplified command  ActiveRecord  Migration drop table  table name

User · Answer

Write your migration manually  E g  run rails g migration DropUsers   As for the code of the migration I m just gonna quote Maxwell Holder s post Rails Migration Checklist  BAD - running rake db migrate and then rake db rollback will fail  class DropUsers  lt  ActiveRecord  Migration   def change     drop table  users   end end   GOOD - reveals intent that migration should not be reversible  class DropUsers  lt  ActiveRecord  Migration   def up     drop table  users   end    def down     fail ActiveRecord  IrreversibleMigration   end end   BETTER - is actually reversible  class DropUsers  lt  ActiveRecord  Migration   def change     drop table  users do  t        t string  email  null  false       t timestamps null  false     end   end end

User · Answer

rails g migration drop users edit the migration       class DropUsers  lt  ActiveRecord  Migration       def change         drop table  users do  t            t string  name           t timestamps         end       end     end    rake db migrate

User · Answer

Drop Table Migration  run -   rails generate migration DropTablename  exp -   rails generate migration DropProducts

[ruby-on-rails] Rails DB Migration - How To Drop a Table?

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