在postgres中，您可以使用 generate_series() :

select p.product_id, coalesce(t.created_at, gs.dte),
       coalesce(volume, 0),
       coalesce(remaining_volume, 0)
from (select product_id, min(created_at)::min_ca, max(created_at) as max_ca
      from t
      group by product_id
     ) p cross join lateral
     generate_series(min_ca::date, max_ca::date, interval '1 day') gs(dte) left join
     t
     on t.product_id = p.product_id and
        t.created_at::date = gs.dte;