what is the minimum total cost for a hospital that includes a drug called zidovudine since 5 years ago?
select min(t1.c1) from ( select sum(cost.cost) as c1 from cost where cost.hadm_id in ( select prescriptions.hadm_id from prescriptions where prescriptions.drug = 'zidovudine' ) and datetime(cost.chargetime) >= datetime(current_time,'-5 year') group by cost.hadm_id ) as t1