import pandas as pd
from datetime import datetime
def audit_change_log(machine_id):
changes = pd.read_sql("SELECT * FROM change_log WHERE machine_id = ? ORDER BY change_date", machine_id)
audit = []
for _, chg in changes.iterrows():
audit.append({'version': chg['version'], 'date': chg['change_date'], 'engineer': chg['engineer'], 'approved_by': chg['approved_by'], 'days_ago': (datetime.now() - chg['change_date']).days})
return pd.DataFrame(audit)