耙分贝：迁移错误 - SQLite3

Question

执行 rake db:migrate 命令时，我不断收到以下错误：

rake 中止！ 发生错误，此迁移和所有后续迁移均已取消： SQLite3::SQLException：重复的列名：电子邮件：ALTER TABLE "users" ADD "email" varchar(255) DEFAULT '' NOT NULL

我也尝试了命令 - bundle exec rake db:migrate。我跑了 --trace 并得到了信息。以下。

** 调用 db:migrate (first_time) ** 调用环境（first_time） ** 执行环境 ** 调用 db:load_config (first_time) ** 执行 db:load_config ** 执行数据库：迁移 == AddDeviseToUsers: 迁移 ============================================= == -- change_table(:users) 耙中止！ 发生错误，此迁移和所有后续迁移均已取消：

SQLite3::SQLException: 重复列名: 电子邮件: ALTER TABLE "users" ADD "email" varchar(255) DEFAULT '' NOT NULL /usr/local/rvm/gems/ruby-1.9.3-p392/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in initialize' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:innew' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in prepare' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:134:inexecute' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/sqlite_adapter.rb:278:in block in execute' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_adapter.rb:280:inblock in log' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb:20:in instrument' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_adapter.rb:275:inlog' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/sqlite_adapter.rb:278:in execute' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/schema_statements.rb:264:inadd_column' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/sqlite_adapter.rb:400:in add_column' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/schema_definitions.rb:479:inblock in string' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/schema_definitions.rb:468:in each' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/schema_definitions.rb:468:instring' /Users/ddorrick/code/onrails/db/migrate/20130321170702_add_devise_to_users.rb:5:in block in up' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/schema_statements.rb:243:inchange_table' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:466:in block in method_missing' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:438:inblock in say_with_time' /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/benchmark.rb:280:in measure' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:438:insay_with_time' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:458:in method_missing' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:334:inmethod_missing' /Users/ddorrick/code/onrails/db/migrate/20130321170702_add_devise_to_users.rb:3:in up' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:370:inup' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:410:in block (2 levels) in migrate' /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/benchmark.rb:280:inmeasure' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:410:in block in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/connection_pool.rb:129:inwith_connection' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:389:in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:528:inmigrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:720:in block (2 levels) in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:775:incall' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:775:in block in ddl_transaction' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/database_statements.rb:192:intransaction' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/transactions.rb:208:in transaction' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:775:inddl_transaction' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:719:in block in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:700:ineach' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:700:in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:570:inup' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:551:in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/railties/databases.rake:179:inblock (2 个级别) in ' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:228:in call' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:228:inblock 在执行' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:223:in each' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:223:inexecute' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:166:in block in invoke_with_call_chain' /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/monitor.rb:211:inmon_synchronize' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:159:in invoke_with_call_chain' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/task.rb:152:ininvoke' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:143:in invoke_task' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:101:inblock (2 个级别) in top_level' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:101:in each' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:101:inblock in top_level' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:110:in run_with_threads' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:95:intop_level' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:73:in block in run' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:160:instandard_exception_handling' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/lib/rake/application.rb:70:in run' /usr/local/rvm/gems/ruby-1.9.3-p392@global/gems/rake-10.0.3/bin/rake:33:in' /usr/local/rvm/gems/ruby-1.9.3-p392@global/bin/rake:19:in load' /usr/local/rvm/gems/ruby-1.9.3-p392@global/bin/rake:19:in' /usr/local/rvm/gems/ruby-1.9.3-p392/bin/ruby_noexec_wrapper:14:in eval' /usr/local/rvm/gems/ruby-1.9.3-p392/bin/ruby_noexec_wrapper:14:in' 任务：TOP => db:migrate

Answer 1

First of all, if you're using devise for authentication,email field is provided by default. The source for the error is: "The email field is also present in users table. That's why whenever you're run db:migrate it shows duplicate column error.

So drop the users table by giving command ActiveRecord::Migration.drop_table(:users)"  in rails console.

Then, give  rails g model user user_name:string mobile_number:integer

Hope it will helps.