คำนวณจำนวนผู้ป่วยที่ได้รับการสั่งจ่ายโซฟรานในระหว่างปีนี้ ไม่จำเป็นต้องใช้ตารางทั้งหมด
calculate the number of patients who have been prescribed zofran during this year.It is not neccessary to use all the tables.
 patient:  uniquepid [ text]  patienthealthsystemstayid [ number]  patientunitstayid [ number]  gender [ text]  age [ text]  ethnicity [ text]  hospitalid [ number]  wardid [ number]  admissionheight [ number]  admissionweight [ number]  dischargeweight [ number]  hospitaladmittime [ time]  hospitaladmitsource [ text]  unitadmittime [ time]  unitdischargetime [ time]  hospitaldischargetime [ time]  hospitaldischargestatus [ text] 
SELECT COUNT(DISTINCT patient.uniquepid) FROM patient WHERE patient.patientunitstayid IN (SELECT medication.patientunitstayid FROM medication WHERE medication.drugname = 'zofran' AND DATETIME(medication.drugstarttime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-0 year'))