CREATE OR REPLACE FORCE VIEW t_quant (ITEM, TOT_QUAN)

AS

SELECT item ,

NVL(SUM(import_d.item),0)-NVL(SUM(drug_d.item),0) tot_quan

FROM import_d,drug_d

WHERE import_d.item = drug_d.item

GROUP BY item;

Group by import_d.item, drug_d.item