구름 아카이브

* CEIL - 소수점 첫째 자리에서 올림

* FLOOR - 소수점 첫째 자리에서 내림

* ROUND - 숫자를 각 자리에서 반올림

* TRUNCATE(숫자, 버릴 자릿수) - 숫자를 버릴 자릿수 아래로 버림

* ABS - 절대값

* POWER - 제곱

* SQRT - 양수 x 에 대한 제곱근을 반환

Average Population
https://www.hackerrank.com/challenges/average-population/problem

SELECT Floor(AVG(population))
FROM CITY

Weather Observation Station 2
https://www.hackerrank.com/challenges/weather-observation-station-2/submissions/database/293205884

SELECT  ROUND(SUM(LAT_N),2) AS lat  
       ,ROUND(SUM(LONG_W),2) AS lon
FROM STATION

Weather Observation Station 18 - Medium 
https://www.hackerrank.com/challenges/weather-observation-station-18/problem

SELECT ROUND(ABS(MIN(LAT_N)-MAX(LAT_N)) + ABS(MIN(LONG_W)-MAX(LONG_W)),4)
FROM STATION

Weather Observation Station 19 - Medium 
https://www.hackerrank.com/challenges/weather-observation-station-19/problem

SELECT TRUNCATE(SQRT( POWER(MAX(LAT_N)-MIN(LAT_N),2) + POWER(MAX(LONG_W)-MIN(LONG_W),2) ),4)
FROM STATION

Average Population of Each Continent
https://www.hackerrank.com/challenges/average-population-of-each-continent/problem

SELECT COUNTRY.CONTINENT, FLOOR(AVG(city.population)) FROM CITY
       INNER JOIN COUNTRY ON COUNTRY.Code = CITY.CountryCode
       
GROUP BY COUNTRY.CONTINENT