Error to Migrate DB Rails

Question

Im trying to use this migration but i keep getting the error, like these

This is my Migration file

class CreateEmployees < ActiveRecord::Migration
  def self.up
    create_table :employees do |t|
      t.string :name 
      t.date :hiredate 
      t.float :salary 
      t.boolean :fulltime , :default => true 
      t.integer :vacationdays 
      t.text :comments
    end 
  end

  def self.down
    drop_table :employees
  end
end

when i try to execute rake db:migrate get this error:

== CreateEmployees: migrating ================================================ -- create_table(:employees) rake aborted! An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: table "employees" already exists: CREATE TABLE "employees" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar (255), "hiredate" date, "salary" float, "fulltime" boolean DEFAULT 't', "vacationdays" integer, "comments" text) /Library/Ruby/Gems/2.0.0/gems/sql ite3-1.3.8/lib/sqlite3/database.rb:91:in initialize' /Library/Ruby/Gems/2.0.0/gems/sqlite3-1.3.8/lib/sqlite3/database.rb:91:innew' /Library/Ruby/Gems/2.0.0/gems/sqlite3-1.3.8/lib/sqlite3/database.rb:91:in prepare' /Library/Ruby/Gems/2.0.0/gems/sqlite3-1.3.8/lib/sqlite3/database.rb:134:inexecute' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/sqlite3_adapter.rb:328:in block in execute' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:425:inblock in log' /Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/notifications/instrumenter.rb:20:in instrument' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:420:inlog' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/sqlite3_adapter.rb:328:in execute' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:190:increate_table' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:625:in block in method_missing' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:597:inblock in say_with_time' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:597:in say_with_time' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:617:inmethod_missing' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:383:in method_missing' /Users/YuriAguirre/Documents/Aptana Studio 3 Workspace/company/db/migrate/20130923140626_create_employees.rb:3:inup' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:534:in up' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:574:inexec_migration' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:555:in block (2 levels) in migrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:554:inblock in migrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:553:inmigrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:709:in migrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:959:inblock in execute_migration_in_transaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:1005:in block in ddl_transaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:202:inblock in transactio n' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:210:in within_new_transact ion' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:202:intransaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/transactions.rb:209:in transaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:1005:inddl_transaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:958:in execute_migration_in_transaction' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:920:inblock in migrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:916:in each' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:916:inmigrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:764:in up' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/migration.rb:742:inmigrate' /Library/Ruby/Gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/railties/databases.rake:42:in `block (2 levels) in ' Tasks: TOP => db:migrate (See full trace by running task with --trace)

You've received answer: SQLite3::SQLException: table "employees" already exists You've provided not enough details to judge why you have this table created, maybe you've made it by hand, maybe it was created by another migration, who knows. — zrl3dx
Oh now i saw, im a newbie at Rails how can i recreate or drop that table that already exist? — Ytipsh
The Good Way is to use migrations for all changes made to db, so you won't get lost later. I don't know if you want to create that table from scratch or modify it, it latter one you should use add_column :table_name, :column_name, :column_type syntax — zrl3dx
Oh, got it, but i still don't know how i can drop that table now and create the table again haha cause i have no ideia if i have created the table with the right statement. — Ytipsh
You've got answer in migration you provided ;) Just write drop_table :employees in self.up part (or change instead of both self.up and self.down) or remove it by hand from sqlite console. — zrl3dx

zrl3dx zrl3dx · Accepted Answer · 2013-09-23T15:14:43

As I've written in comment, you are receiving that error because of:

SQLite3::SQLException: table "employees" already exists

Which simply means you already have that column in your database. You can resolve that in few ways:

changing migration to modify instead of create:

class CreateEmployees < ActiveRecord::Migration
  def self.up
    add_column :employees, :name, :string 
    (...)
    end 
  end

  def self.down
    remove_column :employees, :name
  end
end

add another migration which will drop whole table (obviously, that one should be with earlier timestamp than modifying one so table will be dropped first and then created again):
```
 class RemoveEmployees < ActiveRecord::Migration
   def change
     drop_table :employees
   end
 end
```
drop table by hand from console, but that's not a very good option as you should learn to use migrations for altering your database, of course that w'd be the fastest one (if you know how to use console) and will make no harm if that's just some learning project, but still, you should learn good habits when you can.

You might also want to use newer syntax (AFAIK) def change instead of self.up and self.down, less letters to type and less duplication ;)

Error to Migrate DB Rails

4 Answers