text: .mode columns
  .headers on
  .nullvalue NULL
  
  -- How many health professionals and how much money (spent on health 
  -- professionals’ salaries) are every head of Unit responsible for?
  
  SELECT head, Unit.name AS unitName, Unit.hospital AS hospitalName, SUM(baseSalary+extraSalary) AS totalPaid, COUNT(*) AS numberOfHealthProfessionals
  FROM Unit JOIN WorksAt
  ON (Unit.name=WorksAt.unitName AND Unit.hospital=WorksAt.hospitalName)
  JOIN HealthProfessional ON (HealthProfessional.cc=healthProfessional)
  GROUP BY head
  ORDER BY totalPaid DESC;
  