นับจำนวนผู้ป่วยที่ได้รับการฉีดวัคซีนที่จำเป็นภายใน 2 เดือนหลังจากได้รับขั้นตอนการถ่ายเซลล์แบบแพ็ค ไม่จำเป็นที่จะต้องใช้ตารางทั้งหมด
count the number of patients that received a vaccination nec procedure within 2 months after having received a packed cell transfusion procedure.It is not neccessary to use all the tables.
 prescriptions:  row_id [ number]  subject_id [ number]  hadm_id [ number]  startdate [ time]  enddate [ time]  drug [ text]  dose_val_rx [ text]  dose_unit_rx [ text]  route [ text] 
SELECT COUNT(DISTINCT t1.subject_id) FROM (SELECT admissions.subject_id, procedures_icd.charttime FROM procedures_icd JOIN admissions ON procedures_icd.hadm_id = admissions.hadm_id WHERE procedures_icd.icd9_code = (SELECT d_icd_procedures.icd9_code FROM d_icd_procedures WHERE d_icd_procedures.short_title = 'packed cell transfusion')) AS t1 JOIN (SELECT admissions.subject_id, procedures_icd.charttime FROM procedures_icd JOIN admissions ON procedures_icd.hadm_id = admissions.hadm_id WHERE procedures_icd.icd9_code = (SELECT d_icd_procedures.icd9_code FROM d_icd_procedures WHERE d_icd_procedures.short_title = 'vaccination nec')) AS t2 ON t1.subject_id = t2.subject_id WHERE t1.charttime < t2.charttime AND DATETIME(t2.charttime) BETWEEN DATETIME(t1.charttime) AND DATETIME(t1.charttime, '+2 month')