บอกฉันหน่อยว่าค่าใช้จ่ายเฉลี่ยของโรงพยาบาลที่มีบาดแผลติดเชื้อตั้งแต่ปี 2548 ไม่จำเป็นต้องใช้ทุกโต๊ะ
tell me the average total cost of a hospital that contains wound infection since 2105?It is not neccessary to use all the tables.
 diagnosis:  diagnosisid [ number]  patientunitstayid [ number]  diagnosisname [ text]  diagnosistime [ time]  icd9code [ text] 
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 diagnosis.patientunitstayid FROM diagnosis WHERE diagnosis.diagnosisname = 'wound infection')) AND STRFTIME('%y', cost.chargetime) >= '2105' GROUP BY cost.patienthealthsystemstayid) AS t1