-- Add 'unknown' to billing_method check constraint
ALTER TABLE tticket_worklog DROP CONSTRAINT IF EXISTS tticket_worklog_billing_method_check;

ALTER TABLE tticket_worklog ADD CONSTRAINT tticket_worklog_billing_method_check 
CHECK (billing_method::text = ANY (ARRAY[
    'prepaid_card', 
    'invoice', 
    'internal', 
    'warranty', 
    'unknown'
]));