Ruby-on-rails PG::DuplicateTable: 错误

PG::DuplicateTable: ERROR

提问by Leag Er

When I run rake db:migrate I get following output:

当我运行 rake db:migrate 时，我得到以下输出：

== 20141219011612 CreatePost: migrating ======================================= -- create_table("posts") rake aborted! StandardError: An error has occurred, this and all later migrations canceled: == 20141219011612 Postposts: migrating ======================================= -- create_table("posts") rake aborted! StandardError: An error has occurred, this and all later migrations canceled:

PG::DuplicateTable: ERROR: relation "posts" already exists : CREATE TABLE "posts" ("id" serial primary key, "post" text, "release_date" timestamp, "created_at" timestamp, "updated_at" timestamp) /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in async_exec' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in block in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in instrument' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in create_table' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in block in method_missing' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in block in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in method_missing' /home/admin/Desktop/postr/db/migrate/20141219011612_post_posts.rb:3:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:598:in exec_migration' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in block (2 levels) in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in block in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in block in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in block in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:209:in within_new_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/transactions.rb:208:intransaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in each' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in block (2 levels) in ' ActiveRecord::StatementInvalid: PG::DuplicateTable: ERROR: relation "posts" already exists : CREATE TABLE "posts" ("id" serial primary key, "post" text, "release_date" timestamp, "created_at" timestamp, "updated_at" timestamp) /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in async_exec' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in block in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in instrument' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in create_table' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in block in method_missing' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in block in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in method_missing' /home/admin/Desktop/postr/db/migrate/20141219011612_post_posts.rb:3:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:598:in exec_migration' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in block (2 levels) in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in block in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in block in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in block in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:209:in within_new_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/transactions.rb:208:intransaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in each' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in block (2 levels) in ' PG::DuplicateTable: ERROR: relation "posts" already exists /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in async_exec' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in block in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in instrument' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in create_table' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in block in method_missing' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in block in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in method_missing' /home/admin/Desktop/postr/db/migrate/20141219011612_post_posts.rb:3:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:598:in exec_migration' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in block (2 levels) in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in block in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in block in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in block in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:209:in within_new_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/transactions.rb:208:intransaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:952:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in each' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:785:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in block (2 levels) in ' Tasks: TOP => db:migrate (See full trace by running task with --trace)

== 20141219011612 CreatePost：迁移 ======================================== -- create_table("帖子") 抽水中止！标准错误：发生错误，这次和所有后来的迁移都取消了：== 20141219011612 Postposts：迁移 ============================== ========== -- create_table("posts") 抽水中止！标准错误：发生错误，这次和所有以后的迁移都取消了：

PG::DuplicateTable：错误：关系“posts”已经存在：CREATE TABLE“posts”（“id”序列主键、“post”文本、“release_date”时间戳、“created_at”时间戳、“updated_at”时间戳）/home/ admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in async_exec' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block in execute' /home/admin/.rvm/gems/ ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:inblock in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in 仪器'/home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1 .8/lib/active_record/connection_adapters/abstract_adapter.rb:367:in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1。 8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:increate_table' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in 阻止method_missing' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in block in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in say_with_time' /home/admin/.rvm/gems /ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:641:in method_missing' /home/admin/Desktop/postr/db/migrate/20141219011612_post_posts.rb:3:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1。 8/lib/active_record/migration.rb:598:in exec_migration' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in block (2 levels) in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration .rb:578:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in migrate' /home/admin/ .rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in block in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in 阻止 ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in block in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:209:in inside_new_transaction' /home/admin/ .rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/transactions.rb:208:intransaction' /home/admin/.rvm/gems/ruby-2.1。 5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in ddl_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:990:in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record /migration.rb:952:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in each' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:948:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:807:in up' /home/ admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb： 785：输入migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/railties/databases.rake:34:in 'ActiveRecord::StatementInvalid: PG::DuplicateTable: 错误：关系“posts”已经存在：CREATE TABLE“posts”（“id”序列主键，“post”文本，“release_date”时间戳，“ created_at”时间戳，“updated_at”时间戳）/home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in async_exec' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block in执行'/home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:373:in block in log' /home/admin/.rvm/gems/ruby-2.1.5/gems/activesupport-4.1.8/lib/active_support/notifications/instrumenter.rb:20:in instrument'/home/admin/.rvm/gems /ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract_adapter.rb:367:inlog' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in 执行'/home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:205:in create_table' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:649:in block in method_missing' /home/admin/ .rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in block in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:621:in say_with_time' /home/admin/.rvm/gems/ruby-2.1.5/gems/ activerecord-4.1.8/lib/active_record/migration.rb:641:in method_missing' /home/admin/Desktop/postr/db/migrate/20141219011612_post_posts.rb:3:in up' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb :598:in exec_migration' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:579:in block (2 levels) in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:578:in block in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' / home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:577:in migrate' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:752:in 迁移' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:991:in block in execute_migration_in_transaction' /home/admin/.rvm/gems/ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/migration.rb:1037:in ddl_transaction 中的块 /home/admin/.rvm/gems /ruby-2.1.5/gems/activerecord-4.1.8/lib/active_record/connection_adapters/abstract/database_statements.rb:201:in block in transaction' 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I don't understund how this is possible, bescause In scheme file I don't have post table.

我不明白这是怎么可能的，因为在方案文件中我没有发布表。

回答by Bill Doughty

Somehow, you ended up with a table named 'posts' in your database. Perhaps from a prior migration that you deleted without rolling back? If you don't care about any of your data in the database, you can run

不知何故，您最终在数据库中得到了一个名为“posts”的表。也许是从您之前删除的迁移中删除而没有回滚？如果您不关心数据库中的任何数据，则可以运行

rake db:drop db:create db:migrate

to bring your development database inline with your current migrations.

使您的开发数据库与您当前的迁移保持一致。

If you have data in other tables you don't want to lose, open the database console and drop the posts table manually:

如果您不想丢失其他表中的数据，请打开数据库控制台并手动删除帖子表：

$ rails db

# drop table posts;

Then run db:migrateagain.

然后db:migrate再次运行。

回答by djadam

Check your db/schema.rb

检查您的 db/schema.rb

You most likely have the same table being created there in addition to a migration in db/migrate/[timestamp]your_migration

除了 db/migrate/[timestamp]your_migration 中的迁移之外，您很可能在那里创建了相同的表

You can delete the db/migrate/[timestamp]your_migration if it is a duplicate of the one found in the schema and it should work.

如果 db/migrate/[timestamp]your_migration 与架构中找到的重复并且应该可以工作，则可以删除它。

回答by Adam Grant

In case this helps anyone else, I realized that I had been using a schema.rb file that was generated while using MySQL. After transitioning to Postgres, I simply forgot I would need to run rake db:migratebefore I could use rake db:schema:load

如果这对其他人有帮助，我意识到我一直在使用在使用 MySQL 时生成的 schema.rb 文件。转换到 Postgres 后，我只是忘记了我需要运行rake db:migrate才能使用rake db:schema:load

回答by Sandip Subedi

One of the hack I found was to put pry before you are creating the table on the migration file.

我发现的一个技巧是在您在迁移文件上创建表之前放置 pry。

require 'pry'
binding.pry

create_table :your_table_name

and drop that table:

并删除该表：

drop_table :your_table_name

After that you can remove the drop_tableline and it will work fine!

之后，您可以删除该drop_table行，它会正常工作！

回答by Duarte Martins

kill the current postgres process:

杀死当前的 postgres 进程：

sudo kill -9 `ps -u postgres -o pid` 

start postgres again:

再次启动 postgres：

brew services start postgres

drop, create, and migrate table:

删除、创建和迁移表：

rails db:drop db:create db:migrate