instruction: how much difference does patient 031-4987 have in heartrate measured at 2104-12-30 22:20:00 compared to the value measured at 2104-12-30 22:15:00?
response: SELECT (SELECT vitalperiodic.heartrate FROM vitalperiodic WHERE vitalperiodic.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '031-4987')) AND NOT vitalperiodic.heartrate IS NULL AND vitalperiodic.observationtime = '2104-12-30 22:20:00') - (SELECT vitalperiodic.heartrate FROM vitalperiodic WHERE vitalperiodic.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '031-4987')) AND NOT vitalperiodic.heartrate IS NULL AND vitalperiodic.observationtime = '2104-12-30 22:15:00')