SQL在Rails中查询的位置

Question

当我输入：

User.where(:created_at => "2015-08-06".."2015-08-07").where("updated_at > created_at + 1.day").count

返回错误：

SELECT COUNT(*) FROM `users` WHERE `users`.`created_at` BETWEEN '2015-08-06' AND '2015-08-07' AND (updated_at > created_at + 1.day)ActiveRecord::StatementInvalid: Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'day)' at line 1: SELECT COUNT(*) FROM `users`  WHERE `users`.`created_at` BETWEEN '2015-08-06' AND '2015-08-07' AND (updated_at > created_at + 1.day)

from /home/guinness/shared/bundle/ruby/2.1.0/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:245:in query'

这怎么了 如您所知，我想知道注册1天后保留了多少用户。

Answer 1

1.day是ruby语法，不是sql。 尝试这个：

 User.where(:created_at => "2015-08-06".."2015-08-07").where("updated_at > DATE_ADD(created_at, INTERVAL 1 DAY)").count

参见http://www.w3schools.com/sql/func_date_add.asp

Answer 2

像这样尝试

User.where(:created_at => "2015-08-06".."2015-08-07").where("updated_at > ?", created_at + 1.day).count