Reigning weightlifting champions

A reigning champion is a champion who's won both the previous and current years' competitions. To determine if a champion is reigning, the previous and current years' results need to be in the same row, in two different columns.

This exercise is part of the course

PostgreSQL Summary Stats and Window Functions

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Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

SELECT
  -- Return each year's champions' countries
  ___,
  ___ AS champion
FROM Summer_Medals
WHERE
  Discipline = 'Weightlifting' AND
  Event = '69KG' AND
  Gender = 'Men' AND
  Medal = ___;