[MySQL] HackerRank - Weather Observation Station 4

문제

https://www.hackerrank.com/challenges/weather-observation-station-4/problem

Weather Observation Station 4 | HackerRank

Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.

where LAT_N is the northern latitude and LONG_W is the western longitude.

For example, if there are three records in the table with CITY values 'New York', 'New York', 'Bengalaru', there are 2 different city names: 'New York' and 'Bengalaru'. The query returns , because total number of records - number of unique city names = 3 - 2 = 1

 

정답

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

 

 

오,, 그냥 기초문제를 풀어넘기다보니 어느세 SQL 별 한개 뱃지를 받았다. 이거 은근 수집욕구가 올라오는 군...!

짜잔