instruction: so whats the last weight of patient 4718 until 30 months ago?
response: SELECT chartevents.valuenum FROM chartevents WHERE chartevents.icustay_id IN (SELECT icustays.icustay_id FROM icustays WHERE icustays.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 4718)) AND chartevents.itemid IN (SELECT d_items.itemid FROM d_items WHERE d_items.label = 'admit wt' AND d_items.linksto = 'chartevents') AND DATETIME(chartevents.charttime) <= DATETIME(CURRENT_TIME(), '-30 month') ORDER BY chartevents.charttime DESC LIMIT 1