두 개의 쿼리를 union으로 합치는 방법
#MySQL
(SELECT CITY, LENGTH(CITY)
FROM STATION
WHERE LENGTH(CITY)=(SELECT MIN(LENGTH(CITY))
FROM STATION
) #처음 쿼리는 길이가 가장 적고, 알파벳 순 가장 처음 도시
ORDER BY 1
LIMIT 1)
UNION #두 가지의 seperate queries를 하나로
(SELECT CITY, LENGTH(CITY)
FROM STATION
WHERE LENGTH(CITY)=(SELECT MAX(LENGTH(CITY))
FROM STATION
)
) #두번째 쿼리는 길이가 가장 긴 도시
# 복잡한 where 문 대신 사용할 수 있는
(SELECT CITY, LENGTH(CITY)
FROM STATION
ORDER BY LENGTH(CITY), CITY ASC
LIMIT 1
)
UNION
(SELECT CITY, LENGTH(CITY)
FROM STATION
ORDER BY 2 DESC
LIMIT 1
)