问如何数据库:安装mysql2数据库？

EN

$ RAILS_ENV=development bundle exec rake db:setup 

rake aborted! 
Mysql2::Error::ConnectionError: 
Can't connect to local MySQL server through socket '/var/mysql/mysql.sock' (2)

development:
  adapter: mysql2
  socket: /var/mysql/mysql.sock
  database: wagn_development
  username: user
  password: user
  host: localhost

test:
  adapter: mysql2
  socket: /var/mysql/mysql.sock
  database: wagn_test
  username: user
  password: user
  host: localhost

production:
  adapter: mysql2
  socket: /var/mysql/mysql.sock
  database: wagn_production
  username: user
  password: user
  host: localhost