無法在Ruby on Rails中連接到MySQL

Question

我已經運行gem install mysql2，將lib文件添加到bin文件夾中，就像它說的那樣，mysql2在gem文件中。哪裏不對？

# MySQL. Versions 4.1 and 5.0 are recommended. 
# 
# Install the MYSQL driver 
# gem install mysql2 
# 
# Ensure the MySQL gem is defined in your Gemfile 
# gem 'mysql2' 
# 
# And be sure to use new-style password hashing: 
# http://dev.mysql.com/doc/refman/5.0/en/old-client.html 
development: 
    adapter: mysql2 
    encoding: utf8 
    reconnect: false 
    database: dealers 
    pool: 5 
    username: fredric 
    password: test 
    host: localhost 

Mysql2::Error (Access denied for user 'fredric'@'localhost' (using password: YES)): 
    mysql2-0.3.11-x86 (mingw32) lib/mysql2/client.rb:44:in `connect' 
    mysql2-0.3.11-x86 (mingw32) lib/mysql2/client.rb:44:in `initialize' 
    activerecord (3.2.1) lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `new' 
    activerecord (3.2.1) lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `mysql2_connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:277:in `new_connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:287:in `checkout_new_connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:235:in `block (2 levels) in checkout' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:230:in `loop' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:230:in `block in checkout' 
    C:/Ruby193/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:229:in `checkout' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:374:in `retrieve_connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_specification.rb:168:in `retrieve_connection' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_specification.rb:142:in `connection' 
    activerecord (3.2.1) lib/active_record/query_cache.rb:67:in `rescue in call' 
    activerecord (3.2.1) lib/active_record/query_cache.rb:61:in `call' 
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call' 
    activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `_run__874471498__call__280582312__callbacks' 
    activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback' 
    activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_call_callbacks' 
    activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks' 
    actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/reloader.rb:65:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/remote_ip.rb:31:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call' 
    railties (3.2.1) lib/rails/rack/logger.rb:26:in `call_app' 
    railties (3.2.1) lib/rails/rack/logger.rb:16:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/request_id.rb:22:in `call' 
    rack (1.4.1) lib/rack/methodoverride.rb:21:in `call' 
    rack (1.4.1) lib/rack/runtime.rb:17:in `call' 
    activesupport (3.2.1) lib/active_support/cache/strategy/local_cache.rb:72:in `call' 
    rack (1.4.1) lib/rack/lock.rb:15:in `call' 
    actionpack (3.2.1) lib/action_dispatch/middleware/static.rb:53:in `call' 
    railties (3.2.1) lib/rails/engine.rb:479:in `call' 
    railties (3.2.1) lib/rails/application.rb:220:in `call' 
    rack (1.4.1) lib/rack/content_length.rb:14:in `call' 
    railties (3.2.1) lib/rails/rack/log_tailer.rb:14:in `call' 
    rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service' 
    C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service' 
    C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run' 
    C:/Ruby193/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread' 


    Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/_trace.erb (3.0ms) 
    Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (39.0ms) 
    Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (108.0ms) 
[2012-02-05 20:30:54] WARN Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true 

Answer 1

由於您的PRIVILEGES設置，它看起來像訪問控制問題。請記住，localhost是授予權限時%未涵蓋的特殊情況，因爲它將通過本地UNIX套接字而不是端口3306 TCP套接字進行連接。

你應該檢查你可以從應用程序是在使用了mysql命令行工具運行在同一臺機器連接：

mysql --user=frederic --password=test dealers 

你應該得到相同的錯誤在這一點上Mysql2驅動程序。

一般來說，這是通過更新您的補助定額：

GRANT ALL PRIVILEGES ON dealers.* to `frederic`@`localhost` IDENTIFIED BY 'test'