# PostgreSQL primary (sequence) key issue

**URL:** <https://www.ruby-forum.com/t/postgresql-primary-sequence-key-issue/87302>\
**Category:** Rails\
**Created:** [March 1, 2007, 3:42pm UTC](https://www.ruby-forum.com/t/postgresql-primary-sequence-key-issue/87302 "2007-03-01T15:42:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [March 1, 2007, 3:42pm UTC](https://www.ruby-forum.com/t/postgresql-primary-sequence-key-issue/87302/1 "2007-03-01T15:42:41Z")

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Hi,  
I have a sequence set up on one of my tables called seq\_user\_mytable. I  
tried the following with no joy:

set\_primary\_key “user\_id”, :sequence =\> “seq\_user\_mytable” and:

ActiveRecord::Base.seq\_user\_mytable

again with no joy. How do I implement a sequence in Rails/ActiveRecord?

–  
Regards

Andrew

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<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [March 1, 2007, 4:29pm UTC](https://www.ruby-forum.com/t/postgresql-primary-sequence-key-issue/87302/2 "2007-03-01T16:29:49Z")

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Hi,  
I’ve followed the example given here:

[http://ar.rubyonrails.com/classes/ActiveRecord/Base.html#M000367](http://ar.rubyonrails.com/classes/ActiveRecord/Base.html#M000367)

and implemented set\_sequence\_name “seq\_name” in my class. When I try to  
update the user table with a new row from:

[http://localhost:3000/usertbl/new](http://localhost:3000/usertbl/new)

I get the following error message:

RuntimeError: ERROR C23502 Mnull value in column “user\_id” violates  
not-null constraint FexecMain.c L1795 RExecConstraints: INSERT INTO  
usertbl

What am I overlooking here?

–  
Regards

Andrew