Ruby on rails 使用exists优化查询_Ruby On Rails_Ruby On Rails 3

Ruby on rails 使用exists优化查询

ruby-on-rails ruby-on-rails-3

Ruby on rails 使用exists优化查询,ruby-on-rails,ruby-on-rails-3,Ruby On Rails,Ruby On Rails 3,如何使用EXISTS而不是IN-function优化以下mysql查询 Subscriber.first(:conditions => ["email IN(SELECT email from submissions WHERE url = ? AND confirmed != 0)", url], :order => "RANDOM()") 谢谢你的帮助基于exists的sql语法 EXISTS (SELECT email from submissions x WHERE ur

如何使用EXISTS而不是IN-function优化以下mysql查询

Subscriber.first(:conditions => ["email IN(SELECT email from submissions WHERE url = ? AND confirmed != 0)", url], :order => "RANDOM()")

谢谢你的帮助

基于exists的sql语法

EXISTS (SELECT email from submissions x WHERE url = ? AND confirmed != 0 AND x.email = email)