无法从Sequel gem连接mysql

Question

当我尝试从Sequel连接到MySQL时。我收到以下错误：

require 'rubygems'
        require 'sequel'
        DB = Sequel.connect(:adapter => 'mysql', :user => 'root', :host => 'localhost', :database => 'scanty',:password=>'xx')
        DB.tables
    Sequel::DatabaseConnectionError: NameError uninitialized constant Mysql::CLIENT_MULTI_RESULTS
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/adapters/mysql.rb:98:in `connect'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/database.rb:92:in `initialize'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:166:in `call'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:166:in `make_new'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:153:in `available'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:144:in `acquire'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:143:in `synchronize'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:143:in `acquire'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/connection_pool.rb:105:in `hold'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/database.rb:471:in `synchronize'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/adapters/mysql.rb:128:in `execute'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/dataset.rb:314:in `execute'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/adapters/mysql.rb:342:in `execute'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/adapters/mysql.rb:298:in `fetch_rows'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/dataset.rb:185:in `each'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/dataset/convenience.rb:156:in `map'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/dataset/convenience.rb:156:in `map'
        from /opt/local/lib/ruby/gems/1.8/gems/sequel-3.2.0/lib/sequel/adapters/shared/mysql.rb:60:in `tables'
        from (irb):6irb(main):007:0> Sequel::DatabaseConnectionError: NameErro

Answer 1

你需要安装原生MySQL驱动，纯ruby驱动与Sequel不兼容。

根据您的Ruby安装情况，只执行gem install mysql可能就足够了。但是，如果纯Ruby mysql.rb文件已经在Ruby加载路径中，则需要将其从加载路径中删除，或者在调用Sequel.connect之前使用gem('mysql')。

Answer 2

您缺少:host=>'localhost'或您的主机是什么。

此外，这纯粹是出于性能原因，您应该尝试启用:compress。它可以节省大量的带宽。

http://sequel.rubyforge.org/rdoc/files/doc/opening_databases_rdoc.html

编辑：好的，如果不是主机，可能是冲突？参见http://groups.google.com/group/sequel-talk/browse_thread/thread/ee39640a92351f1?pli=1。也就是http://www.mail-archive.com/sequel-talk@googlegroups.com/msg02275.html