Le portail francophone de la géomatique

with tmp as (
    select * from (
        values ('01001', 125, 425, 15000),
                ('01002', 156, 125, 20000),
                ('01004', 30, 650, 12000)) 
         as v(insee_com, densite_pop, altitude, revenus)
) select t.insee_com, 
           unnest(array['densite_pop', 'altitude', 'revenus']) as caracteristiques,
           unnest(array[densite_pop, altitude, revenus]) as valeurs
from tmp t;

insee_com    caracteristiques    valeurs
01001        densite_pop            125
01001        altitude               425
01001        revenus                15000
01002        densite_pop            156
01002        altitude               125
01002        revenus                20000
01004        densite_pop            30
01004        altitude               650
01004        revenus                12000