[해커랭크] Weather Observation Station 4

Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.
The STATION table is described as follows:

 

STATION table

Field	Type
ID	NUMBER
CITY	VARCHAR(21)
STATE	VARCHAR(2)
LAT_N	NUMBER
LONG_W	NUMBER

 

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 , 1 because 

total number of records - number of unique city names = 3 - 2  = 1

 

전체 도시 수를 구해서 고유한 도시 개수(중복되지 않은)를 뺀 값을 구하는 문제입니다.

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

 

출처 : https://www.hackerrank.com/challenges/weather-observation-station-4/problem?isFullScreen=true

Weather Observation Station 4 | HackerRank