instruction: what is the daily minimum ionized calcium value for patient 018-47575 since 3 years ago?
response: SELECT MIN(lab.labresult) FROM lab WHERE lab.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '018-47575')) AND lab.labname = 'ionized calcium' AND DATETIME(lab.labresulttime) >= DATETIME(CURRENT_TIME(), '-3 year') GROUP BY STRFTIME('%y-%m-%d', lab.labresulttime)