mysql - 运行耙数据库 :migrate in Rails fails (table already exists) using mysql-6ren

mysql - 运行耙数据库 :migrate in Rails fails (table already exists) using mysql

转载作者：可可西里更新时间：2023-11-01 07:05:14

我对 Rails 开发还比较陌生。

我正在尝试使用以下命令迁移新创建的表:

$ rake db:migrate

但我经常收到与已存在的表有关的错误。但是每当我尝试运行我的 Rails 应用程序时，我都会收到迁移未决错误。

我不介意删除表，因为我才刚刚开始使用这个应用程序，所以我删除了之前的迁移，并且我运行了 db:migrate 命令，但没有要迁移的东西。然后我将使用以下命令再次添加一个新模型:

$ rails generate model User name:string

然后给了我预期的输出:

    invoke  active_record
      create    db/migrate/20141129134103_create_users.rb
   identical    app/models/user.rb
      invoke    test_unit
   identical      test/models/user_test.rb
   identical      test/fixtures/users.yml

但在那之后我跑了:

$ rake db:migrate --trace

我得到了这个输出:

** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
== 20141129134103 CreateUsers: migrating ======================================
-- create_table(:users)
rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Mysql2::Error: Table 'users' already exists: CREATE TABLE `users` (`id` int(11) auto_increment PRIMARY KEY, `name` varchar(255), `created_at` datetime, `updated_at` datetime) ENGINE=InnoDB/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `query'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in `block in log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in `log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/mysql2_adapter.rb:228:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:460:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in `block in method_missing'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `block in say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in `method_missing'
/home/barry/Documents/Programming/Rails Projects/homework/db/migrate/20141129134103_create_users.rb:3:in `change'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:595:in `exec_migration'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in `block (2 levels) in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in `with_connection'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in `block in execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:1039:in `ddl_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in `execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in `up'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in `block (2 levels) in <top (required)>'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `call'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:172:in `invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:165:in `invoke'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:156:in `invoke_task'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block (2 levels) in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:121:in `run_with_threads'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:106:in `top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:84:in `block in run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:182:in `standard_exception_handling'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:79:in `run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/bin/rake:33:in `<top (required)>'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `load'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `<main>'
ActiveRecord::StatementInvalid: Mysql2::Error: Table 'users' already exists: CREATE TABLE `users` (`id` int(11) auto_increment PRIMARY KEY, `name` varchar(255), `created_at` datetime, `updated_at` datetime) ENGINE=InnoDB
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `query'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in `block in log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in `log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/mysql2_adapter.rb:228:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:460:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in `block in method_missing'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `block in say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in `method_missing'
/home/barry/Documents/Programming/Rails Projects/homework/db/migrate/20141129134103_create_users.rb:3:in `change'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:595:in `exec_migration'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in `block (2 levels) in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in `with_connection'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in `block in execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:1039:in `ddl_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in `execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in `up'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in `block (2 levels) in <top (required)>'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `call'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:172:in `invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:165:in `invoke'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:156:in `invoke_task'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block (2 levels) in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:121:in `run_with_threads'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:106:in `top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:84:in `block in run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:182:in `standard_exception_handling'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:79:in `run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/bin/rake:33:in `<top (required)>'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `load'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `<main>'
Mysql2::Error: Table 'users' already exists
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `query'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in `block in log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in `log'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:303:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/mysql2_adapter.rb:228:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:460:in `create_table'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in `block in method_missing'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `block in say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in `say_with_time'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in `method_missing'
/home/barry/Documents/Programming/Rails Projects/homework/db/migrate/20141129134103_create_users.rb:3:in `change'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:595:in `exec_migration'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in `block (2 levels) in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/benchmark.rb:279:in `measure'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in `with_connection'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in `block in execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:1039:in `ddl_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in `execute_migration_in_transaction'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in `block in migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in `up'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in `migrate'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in `block (2 levels) in <top (required)>'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `call'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:240:in `block in execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:235:in `execute'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:172:in `invoke_with_call_chain'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/task.rb:165:in `invoke'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:156:in `invoke_task'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block (2 levels) in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `each'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:112:in `block in top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:121:in `run_with_threads'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:106:in `top_level'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:84:in `block in run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:182:in `standard_exception_handling'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/lib/rake/application.rb:79:in `run'
/home/barry/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/rake-10.4.0/bin/rake:33:in `<top (required)>'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `load'
/home/barry/.rbenv/versions/2.1.2/bin/rake:23:in `<main>'
Tasks: TOP => db:migrate

正如我所说，在运行我的 Rails 应用程序后，我得到了 Migrations are pending 错误，我似乎无法理解哪里出了问题。如果您需要任何其他文件来帮助诊断此问题，请告诉我。我所做的与教程不同的一件事是我使用 mysql 作为数据库而不是 sqlite3。

提前谢谢你:)

最佳答案

您正在 rails 中删除迁移。然而，实际的 mysql 表本身并没有被触及(删除)，然后你的大部分问题都源于两者不同步的事实。

在这种情况下，您的选择通常是:

- `rake db:migrate:down` # To have rails remove the table and keep in sync*

- delete ('drop table users') the table in mysql and then re-run the migrations.

- Use rake db:reset as indicated by jykim to drop the database.

'schema_migrations 表跟踪这些东西，因此您也可以检查它。

展望 future ，不要只删除迁移而不考虑实际存在的数据库表。使用 rails down migrations 和 db reset 来保持你的 mysql 数据库同步。归根结底，需要正确的是 schema_migrations 表。

关于mysql - 运行耙数据库 :migrate in Rails fails (table already exists) using mysql，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27202970/

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mysql - 运行耙数据库 :migrate in Rails fails (table already exists) using mysql