ผู้ป่วย 16549 ไปโรงพยาบาลครั้งแรกจนถึงปี 2104 เป็นครั้งแรกเมื่อใด?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
when is the first time patient 16549 visited the hospital until 2104?It is not neccessary to use all the tables.
 icustays:  row_id [ number]  subject_id [ number]  hadm_id [ number]  icustay_id [ number]  first_careunit [ text]  last_careunit [ text]  first_wardid [ number]  last_wardid [ number]  intime [ time]  outtime [ time] 
SELECT admissions.admittime FROM admissions WHERE admissions.subject_id = 16549 AND STRFTIME('%y', admissions.admittime) <= '2104' ORDER BY admissions.admittime LIMIT 1