3种链接数据库的方式

# 三种链接数据库的方式：OCI  DBI Activerecordrequire 'activerecord'ActiveRecord::Base.establish_connection(    :adapter => 'oracle',    :database     => "test3_srttest3",    :username => "test3",    :password => "srttest3"  )class Tab_xn_adminright < ActiveRecord::Base  set_table_name "tab_xn_adminright"  endputs Tab_xn_adminright.countrequire 'dbi'def open_connection(open_connection,username,password)    begin      dbh=DBI.connect('DBI:OCI8:'"#{open_connection}", username, password)    rescue DBI::DatabaseError => e      puts "An error occurred"      puts "Error code: #{e.err}"      puts "Error message: #{e.errstr}"    ensure      # disconnect from server      dbh.disconnect if dbh    end  end  puts open_connection("SRT_54","test2","srttest2")require 'oci8'conn = OCI8.new("test3", "srttest3", "test3_srttest3").exec("select * from tab_xn_adminright t where t.admin_id=628") { |r|  puts r.join(',')}