SELECT
    SR1.LINE_ID AS LINE,
    SR1.SEAT_NO AS SEAT_F,
    MAX(SR2.SEAT_NO) AS SEAT_T 
    
FROM
    SEAT_RESERVE AS SR1
    INNER JOIN SEAT_RESERVE AS SR2
    ON SR1.LINE_ID = SR2.LINE_ID
WHERE SR2.SEAT_NO BETWEEN SR1.SEAT_NO AND SR1.SEAT_NO +(3-1)
GROUP BY
    SR1.LINE_ID,
    SR1.SEAT_NO
HAVING
    COUNT(NULLIF(SR2.RSV_STATUS, '1')) =3
ORDER BY SR1.LINE_ID DESC, SR1.SEAT_NO ASC;