Error to Migrate DB Rails - ruby-on-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:in
new'
/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:in
execute'
/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:in
create_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:in
block 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:in
method_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:in
up'
/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:in
exec_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:in
block 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:in
migrate'
/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:in
block 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:in
block 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:in
transaction'
/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:in
ddl_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:in
block 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:in
migrate'
/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:in
migrate'
/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)

Answer 1

Your employees tables is already created in your database. You need to fix it then you can do it in two ways 1. drop the database and create one more or 2. run the down migration then up migration
rake db:drop
rake db:create
rake db:migrate

Answer 2

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 ;)

Answer 3

Your migration is not completely run.You should rollback migration and migrate again.
rails db:rollback
rails db:migrate

Answer 4

You ran that migration already with an error in it. So the migration ran halfway, creating the table incompletely. Rollback that migration, and then run the migration again.