instruction: how much does it cost for the hospital stay of patient 006-47961 in a year before?
response: SELECT SUM(cost.cost) FROM cost WHERE cost.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '006-47961') AND DATETIME(cost.chargetime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year')