instruction: hey what was the first cortisol of patient 57050 in this month?
response: SELECT labevents.valuenum FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 57050) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'cortisol') AND DATETIME(labevents.charttime, 'start of month') = DATETIME(CURRENT_TIME(), 'start of month', '-0 month') ORDER BY labevents.charttime LIMIT 1