HackerRank: SQL 풀이(1~10)

1. Revising the Select Query I

SELECT *
FROM CITY
WHERE CountryCode = 'USA' AND Population > 100000;

2. Revising the Select Query II

SELECT *
FROM CITY
WHERE CountryCode = 'USA' AND Population > 120000;

3. Select All

SELECT *
FROM CITY;

4. Select By ID

SELECT *
FROM CITY
WHERE ID = 1661;

5. Japanese Cities' Attributes

SELECT *
FROM CITY
WHERE COUNTRYCODE = 'JPN';

6. Japanese Cities' Names

SELECT NAME
FROM CITY
WHERE COUNTRYCODE = 'JPN';

7. Weather Observation Station 1

SELECT CITY, STATE
FROM STATION;

8. Weather Observation Station 3

중복제거... 까먹어서 틀림

SELECT CITY
FROM STATION
WHERE ID % 2 = 0;

위에 처럼 하면 중복제거 안 됨.

아래처럼 SELECT DISTINCT 해야함.

SELECT DISTINCT CITY
FROM STATION
WHERE ID % 2 =0;

9. Weather Observation Station 4

SELECT COUNT(CITY) - COUNT(DISTINCT(CITY))
FROM STATION;

10. Weather Observation Station 5

아 ;; 이건 틀렸네요...

SELECT TOP 1 CITY, LEN(CITY) AS LENGTH_CITY
FROM STATION
ORDER BY LENGTH_CITY ASC, CITY ASC

SELECT TOP 1 CITY, LEN(CITY) AS LENGTH_CITY
FROM STATION
ORDER BY LENGTH_CITY DESC, CITY ASC;

SELECT TOP 1 이거랑
ORDER BY 이거 이용하는게 핵심이었네용