ความแตกต่างตามวันในสัปดาห์

-- Select name of the day of the week the request was created 
SELECT ___(___, ___) AS day, 
       -- Select avg time between request creation and completion
       ___(___ - ___) AS duration
  FROM evanston311 
 -- Group by the name of the day of the week and 
 -- integer value of day of week the request was created
 GROUP BY day, EXTRACT(___ ___ ___)
 -- Order by integer value of the day of the week 
 -- the request was created
 ORDER BY EXTRACT(___ ___ ___);