Regular expression to exclude a particular number

I have a Model called Department.

    class Department < ActiveRecord::Base  
      # Associations
      belongs_to :client
      belongs_to :facility

      scope :facility_departments, ->(facility_id) { 
                                  where("facility_id = ? ", facility_id)}

      scope :matching_departments, ->(facility_id, identifier) {facility_departments(facility_id).where("
 ? REGEXP reg_exp ", identifier.to_s).order("weight DESC") }

    end

• In the departments table I have a facility_id, and a regular expression column.
• I also have employees in my application, each one having a department id. In order to identify an employees department, I'm using scope matching_departments in department model (see above).
• Each employee has got an identifier too.
• All employees having a numeric identifier and identifier length = 9 , except 9 zeros (000000000) - should map to department 1.

So what should be the regular expression for department-1 in my departments table? I updated it with (^[0-9]{9,}$) - matching all numeric identifiers with length 9. How can I exclude 9 zeros?