SELECT DATE_PART('hour', dischtime - admittime) FROM mimiciv_hosp.admissions;
SELECT COALESCE(3, 7), COALESCE(null, 8), COALESCE(null, null, null);
SELECT subject_id, ROW_NUMBER() OVER (PARTITION BY subject_id ORDER BY intime) AS rn FROM mimiciv_icu.icustays limit 100;