postgresql working hours simplify query

Question

I need a help with some query simplification (like to avoid repetition etc.)

http://www.sqlfiddle.com/#!17/3607d/1/0

We have 2 objects:

• working hours defined: mon_from, mon_to, tue_from...; if value is null then not working that day

• office defined with it's name and timezone and working_hours_id

Need to simplify a query that finds if that office is working NOW, if office does not have working hours specified, then it is open 24/7.

SELECT
name,
   (CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time,
(workinghours.id IS NULL) OR ((
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN mon_from AND mon_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 1) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN tue_from AND tue_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 2) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN wed_from AND wed_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 3) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN thu_from AND thu_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 4) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN fri_from AND fri_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 5) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN sat_from AND sat_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 6) OR
((CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time BETWEEN sun_from AND sun_to 
 AND EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone) = 7)
) IS True) AS in_workinghours
FROM office
LEFT JOIN workinghours ON (workinghours.id = office.workinghours_id)

Answer 1

SELECT
  name,
  today_time,
  (workinghours.id IS NULL) OR (today_time BETWEEN today_wtime[1] AND today_wtime[2]) AS in_workinghours
FROM office
LEFT JOIN workinghours ON (workinghours.id = office.workinghours_id)
CROSS JOIN LATERAL (
  SELECT
    (CURRENT_TIMESTAMP::time AT TIME ZONE timezone)::time AS today_time,
    CASE EXTRACT(isodow FROM CURRENT_TIMESTAMP AT TIME ZONE timezone)
      WHEN 1 THEN ARRAY[mon_from, mon_to]
      WHEN 2 THEN ARRAY[tue_from, tue_to]
      WHEN 3 THEN ARRAY[wed_from, wed_to]
      WHEN 4 THEN ARRAY[thu_from, thu_to]
      WHEN 5 THEN ARRAY[fri_from, fri_to]
      WHEN 6 THEN ARRAY[sat_from, sat_to]
      WHEN 7 THEN ARRAY[sun_from, sun_to]
    END AS today_wtime) as wtime 

Answer 2

Variation that uses a subquery instead of lateral joins and arrays:

SELECT 
  name,
  ts::time time_at_office,
  (workinghours_id IS NULL) OR
  (CASE EXTRACT(ISODOW FROM ts)
     WHEN 1 THEN ts::time BETWEEN mon_from AND mon_to
     WHEN 2 THEN ts::time BETWEEN tue_from AND tue_to
     WHEN 3 THEN ts::time BETWEEN wed_from AND wed_to
     WHEN 4 THEN ts::time BETWEEN thu_from AND thu_to
     WHEN 5 THEN ts::time BETWEEN fri_from AND fri_to
     WHEN 6 THEN ts::time BETWEEN sat_from AND sat_to
     WHEN 7 THEN ts::time BETWEEN sun_from AND sun_to
   END) AS in_workinghours
FROM 
  (SELECT
     *,
     CURRENT_TIMESTAMP AT TIME ZONE timezone AS ts
   FROM office
   LEFT JOIN workinghours ON (workinghours.id = office.workinghours_id)) owh