บอกฉันจำนวนผู้ป่วยทั้งหมดที่อยู่ในหน่วยดูแล sicu?ไม่จำเป็นต้องใช้ตารางทั้งหมด
tell me the total number of patients who stayed in careunit sicu?It is not neccessary to use all the tables.
 admissions:  row_id [ number]  subject_id [ number]  hadm_id [ number]  admittime [ time]  dischtime [ time]  admission_type [ text]  admission_location [ text]  discharge_location [ text]  insurance [ text]  language [ text]  marital_status [ text]  ethnicity [ text]  age [ number] 
SELECT COUNT(DISTINCT admissions.subject_id) FROM admissions WHERE admissions.hadm_id IN (SELECT transfers.hadm_id FROM transfers WHERE transfers.careunit = 'sicu')