Rake db:迁移错误- SQLite3

Question

在执行rake db:migrate命令时，我一直收到以下错误：

rake中止！发生错误，此迁移和所有后续迁移已取消: SQLite3::SQLException:重复列名: email: ALTER TABLE "users“ADD "email”varchar(255) DEFAULT '‘NOT NULL

我还尝试了命令包exec rake db:migrate。我用--trace得到了信息。如下所示。

** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment ** Invoke db:load_config (first_time) ** Execute db:load_config ** Execute db:migrate == AddDeviseToUsers: migrating users -- change_table(:users) rake中止！发生错误，此迁移和所有后续迁移均已取消：

/usr/local/rvm/gems/ruby-1.9.3-p392/gems/sqlite3-1.3.7/lib/sqlite3/database.rb:91:in异常:重复的列名: email: 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 execute new’/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日志中的本地块‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb:20: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:in’/usr/instrument' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_adapter.rb:275:in/rvm/gems/ruby-1.9.3-字符串‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.’中的p392/gems/activerecord-3.2.12/lib/active_record/connection_adapters/sqlite_adapter.rb:278:in add_column‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.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/abstract/schema_definitions.rb:479:in’12/lib/active_record/connection_adapters/abstract/schema_definitions.rb:468:in本地字符串“/Users/ddorrick/code/onrails/db/migrate/20130321170702_add_devise_to_users.rb:5:in block in up' 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/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/code>up/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:389:in事务迁移‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:720: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:incall’/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:775:in migrate' /usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/migration.rb:528:intransaction‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3.2.12/lib/active_record/transactions.rb:208:in each ddl_transaction‘/usr/local/rvm/gems/ruby-1.9.3-p392/gems/activerecord-3 transaction' 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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.