-- 1

  SELECT 'Mon' 
    UNION 
    SELECT 'Tue'
    UNION 
    SELECT 'Web'
    UNION 
    SELECT 'Thu'
    UNION 
    SELECT 'Fri'
    UNION 
    SELECT 'Sat'
    UNION 
    SELECT 'Sun';



-- 2
WITH RECURSIVE days_cte AS (
  SELECT 'Mon' AS day_name
  UNION ALL
  SELECT
    CASE day_name
      WHEN 'Mon' THEN 'Tue'
      WHEN 'Tue' THEN 'Wed'
      WHEN 'Wed' THEN 'Thu'
      WHEN 'Thu' THEN 'Fri'
      WHEN 'Fri' THEN 'Sat'
      WHEN 'Sat' THEN 'Sun'
      ELSE 'Mon' -- Pro zajištění cyklického opakování
    END
  FROM days_cte
  WHERE day_name != 'Sun'
)
SELECT day_name FROM days_cte;