# "Sequence does not exist" for joined model **URL:** \ **Category:** rubyonrails-talk\ **Created:** [February 24, 2010, 8:44pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661 "2010-02-24T20:44:00Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![11155](https://avatars.discourse-cdn.com/v4/letter/1/d26b3c/32.png) [@11155](https://discuss.rubyonrails.org/u/11155)\ **Post date:** [February 24, 2010, 8:44pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661/1 "2010-02-24T20:44:00Z")
Hello all, I'm in my 5th month on Ruby on Rails and still learning. I have an application that works fine in sqlite3 and then the boss says he wants it migrated to Oracle. Now, I know very little about Oracle, enough to get into trouble. When I did the migration everything went haywire. Well, I've refactored several problems and now I have another. I have two models with a many to many relationship and additional join model. This model has no PK id. When I try to do a create() to this model, BLAM! I get this... Processing ReviewsController#create\_association (for 10.242.2.10 at 2010-02-24 15:29:08) [GET]   Parameters: {"review"=\>{"irb\_id"=\>["35540"]}, "action"=\>"create\_association", "id"=\>"1", "controller"=\>"reviews"} ActiveRecord::StatementInvalid (OCIError: ORA-02289: sequence does not exist: SELECT reviews\_seq.NEXTVAL id FROM dual):   C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-oracle\_enhanced-adapter-1.2.3/lib/active\_record/connection\_adapters/oracle\_enhanced\_adapter.rb:1359:in `log'   C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-oracle_enhanced-adapter-1.2.3/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb:1283:in `select'   C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-oracle\_enhanced-adapter-1.2.3/lib/active\_record/connection\_adapters/oracle\_enhanced\_adapter.rb:606:in `next_sequence_value'   app/controllers/reviews_controller.rb:27:in `create\_association' Rendering C:/RoRApps/ProjectDB/public/500.html (500 Internal Server Error) I believe it's because of the lack of an ID for the joined model. Thank you for any advice here. JohnM ---
**Author:** ![Michael\_Pavling](https://avatars.discourse-cdn.com/v4/letter/m/8dc957/32.png) [@Michael\_Pavling](https://discuss.rubyonrails.org/u/Michael_Pavling)\ **Post date:** [February 24, 2010, 9:01pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661/2 "2010-02-24T21:01:48Z")
In Oracle you need to create ‘sequences’ which populate primary keys. Given the choice, I would steer clear of Oracle with Rails - what’s you boss’ reasoning for wanting to use it over sqlite or mysql? ---
**Author:** ![11155](https://avatars.discourse-cdn.com/v4/letter/1/d26b3c/32.png) [@11155](https://discuss.rubyonrails.org/u/11155)\ **Post date:** [February 24, 2010, 9:49pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661/3 "2010-02-24T21:49:27Z")
Well, I just added an PK ID into the joined table and good to go. Thanks John ---
**Author:** ![11155](https://avatars.discourse-cdn.com/v4/letter/1/d26b3c/32.png) [@11155](https://discuss.rubyonrails.org/u/11155)\ **Post date:** [February 25, 2010, 2:09pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661/4 "2010-02-25T14:09:36Z")
I agree with you. I had the application working fine with SQLite and then he (not just he but the department) wanted the Oracle migration. The reason being is the department is a big Oracle house, even though they have apps with MS-SQL and mySQL. Oh, I did create a sequence also. All works for now. I've had one heck of a time in the migration over to Oracle. Thanks again. John ---
**Author:** ![Michael\_Pavling](https://avatars.discourse-cdn.com/v4/letter/m/8dc957/32.png) [@Michael\_Pavling](https://discuss.rubyonrails.org/u/Michael_Pavling)\ **Post date:** [February 25, 2010, 3:17pm UTC](https://discuss.rubyonrails.org/t/sequence-does-not-exist-for-joined-model/49661/5 "2010-02-25T15:17:22Z")
The last time (spring 2009) I had to use Oracle with Rails, I was finding occasional bugs in the adapter code (which was frustrating). And Oracle's handling of midnight/midday was a bit of a thorny issue too. No idea if it's been advanced, but forewarned is forearmed 🙂