/*which profession gives more working hours per week*/
SELECT occupation,
CASE WHEN workinhoursperweek BETWEEN 0 AND 12 THEN 'quarter '
            WHEN workinhoursperweek BETWEEN 12 AND 24 THEN 'half'
            WHEN workinhoursperweek BETWEEN 24 AND 48 THEN 'full'
            WHEN workinhoursperweek BETWEEN 48 AND 96 THEN 'double'
  END AS workhours,  
  COUNT(*) AS num_people         
FROM person 
GROUP BY  occupation, workhours 
ORDER BY 1,2;