instruction: count the number of patients who had received a microbiological test of the blood, venipuncture in a year before.
response: SELECT COUNT(DISTINCT patient.uniquepid) FROM patient WHERE patient.patientunitstayid IN (SELECT microlab.patientunitstayid FROM microlab WHERE microlab.culturesite = 'blood, venipuncture' AND DATETIME(microlab.culturetakentime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-1 year'))