declare
cursor c is select num_ab,count(num_ex) as nb_emprunt from Emprunt group by num_ab;
begin
for c_t in c
loop
insert into ab_nb values (c_t.num_ab,c_t.nb_emprunt);
end loop;
exception when no_data_found
insert into ab_nb values (c_t.num_ab,-1);
end;
/