instruction: what's the minimum total cost of the hospital that involves a drug called sodium acetate until 4 years ago?
response: 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 = 'sodium acetate') AND DATETIME(cost.chargetime) <= DATETIME(CURRENT_TIME(), '-4 year') GROUP BY cost.hadm_id) AS t1