ruby 连接 mysql

require "rubygems"
require "mysql"
   begin
     dbh = Mysql.real_connect("localhost", "root", "", "test")
     res = dbh.query("SELECT * FROM card")
#     while row = res.fetch_array do
#     printf "%s, %s\n", row["card_id"], row[1]
#     end

  res.each_hash do |f|print "#{f['card_id']} -- #{f['card_info']}\n"end
 
    puts "Server version: " + dbh.get_server_info
    rescue Mysql::Error => e
     puts "Error code: #{e.errno}"
     puts "Error message: #{e.error}"
     puts "Error SQLSTATE: #{e.sqlstate}" if e.respond_to?("sqlstate")
   ensure
     dbh.close if dbh
   end