Question 199

As there is no online judge for question 199 I would like to share my solution:

Would it work?

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with this_week as (
    select distinct student_id
    from snap_test_results
    where date_part('week', current_date) = date_part('week', date)
  ),
last_week as (
      select distinct student_id
    from snap_test_results
    where date_part('week', current_date) - 1 = date_part('week', date)
  )
  
diff as (
      select student_id from this_week
    where student_id not in (
          select student_id from last_week 
      )
  )

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