title: sas proc surveyselect with contstraint on column
body: <p>i'm trying to create a unique sample dataset with <code>proc surveyselect</code> based on 2 columns.
  I have a simple table with <code>person_id</code> and <code>household_id</code>. in this case person_id is my "primary key" which is the main input for creating a sample. BUT i need to make sure that I don't mix household_id between sample and base data.
  So if household_id = 123 is the sample, it is not allowed to appear in the base data (even with another person_id) and vice versa.</p>
  
  <p>do you have a handy idea? all my solution pre- or postprocessing will influence the sample sizes.</p>
  
  <p>Thanks!!
  E.</p>