calcul distances entre point successif méthode avec CTE

variante même requête en utilisant les Command Table Expression

WITH 
line as (SELECT st_geometryn(st_boundary(geom),1) as g 
  FROM bati_pol WHERE no_eca like '11330'), 
series as (SELECT generate_series(1,ST_NumPoints (g) ) as n 
  FROM line)
SELECT  'point '|| n,st_astext(st_pointn(g,n)),
 'point '|| n+1,st_astext(st_pointn(g,n+1)),
 st_distance(st_pointn(g,n),st_pointn(g,n+1)) 
FROM line,series