instruction: what is the average total cost for the hospital involving a procedure called therapeutic antibacterials - third generation cephalosporin the previous year?
response: SELECT AVG(t1.c1) FROM (SELECT SUM(cost.cost) AS c1 FROM cost WHERE cost.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.patientunitstayid IN (SELECT treatment.patientunitstayid FROM treatment WHERE treatment.treatmentname = 'therapeutic antibacterials - third generation cephalosporin')) AND DATETIME(cost.chargetime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year') GROUP BY cost.patienthealthsystemstayid) AS t1