IFNULL (값이 없는 경우 쓸 수 있다) select PT_NAME, PT_NO, GEND_CD, AGE, IFNULL(TLNO, "NONE") as TLNO from PATIENT where AGE = 29 then '장기 대여' else '단기 대여' end ) as RENT_TYPE from CAR_RENTAL_COMPANY_RENTAL_HISTORY where DATE_FORMAT(start_date, "%Y-%m") = '2022-09' order by history_id desc ROUND, TRUNCATE (소수점 처리) select CAR_ID, ROUND(AVG(DATEDIFF(END_DATE, START_DATE) + 1), 1) as AVERAGE_DURATION from CAR_..