Read/insert Chinese data from mysql database saved by php code

I want to use ruby to read/insert data to a mysql database, onto which data were saved by a php code. When I read Chinese data, it does not appear correctly. It appears like 刘佳. But in a php page, it shows Chinese data correctly as 刘佳.

I confirmed the database uses utf-8 charset (CHARSET=utf8 COLLATE=utf8_unicode_ci).

my ruby code

require 'active_record'

class Student < ActiveRecord::Base
end

ActiveRecord::Base.establish_connection(
  adapter:  'mysql2',
  host:     'xxxx',
  username: 'xxxx',
  password: 'xxxx',
  database: 'xxx_db',
  encoding: 'utf8'
)

puts Student.first.name

It outputs an unknown string "刘佳".

How can I read Chinese data correctly and save a new Chinese record to database?

Copyright Notice：Content Author:「Grant Chen」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/24473907/read-insert-chinese-data-from-mysql-database-saved-by-php-code