sample_cross_join.sql

WITH colors(color)
  AS (
    SELECT * 
    FROM unnest(array['red', 'black', 'white'])
  ), sizes(size)
  AS (
    SELECT * 
    FROM unnest(array['S', 'M', 'L', 'XL'])
  ), shoes(type)
  AS (
    SELECT * 
    FROM unnest(array['heels', 'uggs', 'boots', 'wedges'])
  )
SELECT concat_ws(', ', colors.color,sizes.size,shoes.type)
FROM colors
  CROSS JOIN sizes
  CROSS JOIN shoes