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[HackerRank][SQL][JOIN] Basic Join, Top Competitors - 컴도리돌이 Top Competitors | HackerRank Query a list of top-scoring hackers. www.hackerrank.com Problem Julia just finished conducting a coding contest, and she needs your help assembling the leaderboard! Write a query to print the respective hacker_id and name of hackers who achieved full scores for more than one challenge. Order your output in descending order by the total number of challenges in which t.. 더보기
[HackerRank][SQL][JOIN] The Report - 컴도리돌이 The Report | HackerRank Write a query to generate a report containing three columns: Name, Grade and Mark. www.hackerrank.com Problem Ketty gives Eve a task to generate a report containing three columns: Name, Grade and Mark. Ketty doesn't want the NAMES of those students who received a grade lower than 8. The report must be in descending order by grade -- i.e. higher grades are entered first. I.. 더보기
[HackerRank][SQL][JOIN] Average Population of Each Continent - 컴도리돌이 Average Population of Each Continent | HackerRank Query the names of all continents and their respective city populations, rounded down to the nearest integer. www.hackerrank.com Problem Given the CITY and COUNTRY tables, query the names of all the continents (COUNTRY.Continent) and their respective average city populations (CITY.Population) rounded down to the nearest integer. Note: CITY.Countr.. 더보기
[HackerRank][SQL][JOIN] Basic Join, Population Census - 컴도리돌이 Population Census | HackerRank Query the sum of the populations of all cities on the continent 'Asia'. www.hackerrank.com Problem Given the CITY and COUNTRY tables, query the sum of the populations of all cities where the CONTINENT is 'Asia'. -> 아시아에 있는 모든 도시의 인구 수의 합을 출력하시오. Answer select sum(a.population) from city a inner join country b on a.countrycode = b.code where b.continent = "Asia" 더보기