instruction: how many hours has it been since first beta blocker overdose diagnosis of patient 030-42006 on their current hospital visit?
response: SELECT 24 * (STRFTIME('%j', CURRENT_TIME()) - STRFTIME('%j', diagnosis.diagnosistime)) FROM diagnosis WHERE diagnosis.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '030-42006' AND patient.hospitaldischargetime IS NULL)) AND diagnosis.diagnosisname = 'beta blocker overdose' ORDER BY diagnosis.diagnosistime LIMIT 1