MySQL Rails / MySQL2：错误 - 未知数据库
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Rails / MySQL2: Error - Unknown database
提问by KidKola
I'm following a basic tutorial in Linda.
I have been able to install everything properly now, but when I start my Rails server I get this message when I visit localhost:3000:
我正在学习 Linda 的基本教程。我现在已经能够正确安装所有内容，但是当我启动 Rails 服务器时，我在访问时收到此消息localhost:3000：
Unknown database 'simple_cms_development'
and then
进而
Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.0ms)
Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (23.5ms)
Rendered /Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (29.8ms)
回答by Dan Cheail
Have you created the database in MySQL? You should be able to run rake db:createand have Rails create it for you.
您是否在 MySQL 中创建了数据库？您应该能够运行rake db:create并让 Rails 为您创建它。
回答by sami
I had the same error, please run the following command on the Command Prompt:
我有同样的错误，请在命令提示符下运行以下命令：
rake db:create
to solve the problem.
来解决问题。
回答by Jatin Ganhotra
Look for the answers of these questions:
寻找这些问题的答案：
- Have you installed the mysql2 gem?
- Is it mentioned in your Gemfile?
- Did you run the command
rake db:create?
- 您是否安装了 mysql2 gem？
- 它在你的 Gemfile 中提到了吗？
- 你运行命令了
rake db:create吗？
回答by hken27
Sometimes creating database with rake causes issues.
有时使用 rake 创建数据库会导致问题。
You can also create the database inside mysql
也可以在mysql里面创建数据库
Make sure mysql is in the root %PATH% in command prompt type echo %PATH% to check.
确保 mysql 位于命令提示符中的根 %PATH% 中，键入 echo %PATH% 进行检查。
If it isn't in your PATH. Then do a quick google search on windows PATH to get instructions
如果它不在您的 PATH 中。然后在 Windows PATH 上进行快速谷歌搜索以获取说明
Open command prompt
打开命令提示符
type mysql -u root -p
输入 mysql -u root -p
type your password that you created for your root
输入您为 root 创建的密码
To create database
创建数据库
create database simple_cms_development
创建数据库 simple_cms_development
done
完毕
回答by Arvind
was getting the same error but caused was different
得到相同的错误，但导致不同
Mysql2::Error: Unknown database 'rdddd_development'
/Users/.rvm/gems/ruby-2.6.3/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:in connect'
/Users/commeasure/.rvm/gems/ruby-2.6.3/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:ininitialize
/Users/.rvm/gems/ruby-2.6.3/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:inconnect'
/Users/commeasure/.rvm/gems/ruby-2.6.3/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:in初始化
faced this error due to the created method dynamically, code is here
由于动态创建的方法而面临此错误，代码在这里
Role.all.map(&:name).map(&:parameterize).map(&:underscore).each do |name|
define_method("#{name.to_sym}?") do
role.name == name.upcase
end
end
How do I fix this for the temporary purpose just comment it out
我如何解决这个临时目的只是将其注释掉
