ผู้ป่วยที่รับประทาน po pe28 มีจำนวนเท่าใด ไม่จำเป็นต้องใช้ทุกโต๊ะ
what are the numbers of patients who had po pe28 intake?It is not neccessary to use all the tables.
 d_items:  row_id [ number]  itemid [ number]  label [ text]  linksto [ text] 
SELECT COUNT(DISTINCT admissions.subject_id) FROM admissions WHERE admissions.hadm_id IN (SELECT icustays.hadm_id FROM icustays WHERE icustays.icustay_id IN (SELECT inputevents_cv.icustay_id FROM inputevents_cv WHERE inputevents_cv.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'po pe28' AND d_items.linksto = 'inputevents_cv')))