are associations dependent on a database in Rails?

I tested an association on mysql as follows and it works:

User.campaigns

These are the associations in the Models:

Campaign belongs_to :user

User has_many :campaigns

However, when I run it on heroku which uses Postgres, I get the following:

CampaignsController#index (ActiveRecord::StatementInvalid) "PGError: ERROR: column campaigns.user_id does not exist\nLINE 1: SELECT * FROM \"campaigns\" WHERE (\"campaigns\".user_id = 1) \n ^\n: SELECT * FROM \"cam

This is a little worrying because -- if the way I use rails associations depends on the database...hmm...not sure how I can effectively doing any development...thoughts?

From stackoverflow

• Your error indicates the column doesn't exist. Have you run the migrations on Heroku?

  $ heroku rake db:migrate
  

  Angela : Hi, yeah, I did run them....seemed okay, then ran it again and got an error not related to this model....

  Angela : hmm...thinking maybe the migration didn't run completely then...will check, it looked like it did locally though