提供一些背景知识：我一直在构建一个个人博客，与任何其他博客一样，它要求用户身份验证（或至少一个用户）在数据库中。因此，在开发过程中，我使用rails控制台创建了一个用户。
然而，在制作中我需要一个身份验证系统才能创建帖子。所以我所做的是尝试安装设备来处理这个问题，尽管我收到的错误如下所示。
我知道问题与我的数据库中已有的用户表有关，但问题是 - 当尝试运行rake db：migrate以删除表时我得到一个错误，最终，我有在停滞不前。
请告知。
github：https://github.com/Apane/Blogit_blog
rake db:migrate
== DeviseCreateUsers: migrating ==============================================
-- create_table(:users)
rake aborted!
An error has occurred, this and all later migrations canceled:
SQLite3::SQLException: table "users" already exists: CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "email" varchar(255) DEFAULT '' NOT NULL, "encrypted_password" varchar(128) DEFAULT '' NOT NULL, "password_salt" varchar(255) DEFAULT '' NOT NULL, "reset_password_token" varchar(255), "remember_token" varchar(255), "remember_created_at" datetime, "sign_in_count" integer DEFAULT 0, "current_sign_in_at" datetime, "last_sign_in_at" datetime, "current_sign_in_ip" varchar(255), "last_sign_in_ip" varchar(255), "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL) /usr/local/rvm/gems/ruby-1.9.3-p194/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in `initialize'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in `new'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in `prepare'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:134:in `execute'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/sqlite_adapter.rb:278:in `block in execute'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/sqlite_adapter.rb:278:in `execute'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/schema_statements.rb:170:in `create_table'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:466:in `block in method_missing'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `block in say_with_time'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `say_with_time'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:458:in `method_missing'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:334:in `method_missing'
/Users/user/Sites/personal_blog/personal_blog/db/migrate/20130528200110_devise_create_users.rb:3:in `up'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:370:in `up'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:410:in `block (2 levels) in migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:410:in `block in migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:129:in `with_connection'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:389:in `migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:528:in `migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:720:in `block (2 levels) in migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `call'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `block in ddl_transaction'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/transactions.rb:208:in `transaction'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `ddl_transaction'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:719:in `block in migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `each'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:570:in `up'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/migration.rb:551:in `migrate'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/activerecord-3.2.13/lib/active_record/railties/databases.rake:193:in `block (2 levels) in <top (required)>'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:95:in `top_level'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:73:in `block in run'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:160:in `standard_exception_handling'
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.0.4/lib/rake/application.rb:70:in `run'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)
答案 0 :(得分：1)
你的问题在于它在错误中声明：
rake db:migrate
== DeviseCreateUsers: migrating ==============================================
-- create_table(:users
所以发生了什么我相信你试图迁移当前已存在的users表。我也注意到你正在使用设计。您是否运行了以下命令：
rails g devise:install
rails g devise user
rake db:migrate
您还应该将schema.rb版本与db / migrate / * .rb文件进行比较。
<强>更新
您确定要连接到同一个数据库吗？因为我刚注意到你说过
在开发中，我使用rails控制台创建了一个用户。
但在production你遇到了问题。在我看来，您可能无法连接到同一个数据库。另外，建议不要使用SQLite3进行生产。
请检查您要连接到哪个数据库的环境。如果您在Heroku上发布应用程序，这是一种很好的做法。您可能会注意到这使用了Postgres。良好的做法是使用相同的数据库进行开发和生产。
一旦你发现你要连接的数据库和它是什么，我相信这可能是问题所在。
此外，如果您尝试在生产中迁移或类似的东西，您可以使用以下内容：bundle exec rake db:migrate RAILS_ENV=production这将执行生产环境的迁移
答案 1 :(得分：1)
为您的问题
SQLite3 :: SQLException：表“users”已存在：CREATE TABLE“users”（“id”INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL，“email”varchar（255）DEFAULT''NOT NULL，“encrypted_password”varchar（128 ）DEFAULT''NOT NULL，“password_salt”varchar（255）DEFAULT''NOT NULL，“reset_password_token”varchar（255），“remember_token”varchar（255），“remember_created_at”datetime，“sign_in_count”integer DEFAULT 0，“current_sign_in_at “datetime”，last_sign_in_at“datetime”，current_sign_in_ip“varchar（255），”last_sign_in_ip“varchar（255），”created_at“datetime NOT NULL，”updated_at“datetime NOT NULL）
也许您可以检查数据库中的schema_migrations版本。如果您发现您的用户表版本号（我的意思是在您的db / migrate / xxxxxxxxxxxxxx_devise_create_users.rb文件中，并且xxxxxxxxxxxxxx是您的版本号）是在表中的版本后面并且您的users表已经存在，则可以添加用户表版本自己编号跳过创建操作。