Weather Observation Station 4 in SQL | HackerRank Solution

Hello coders, today we are going to solve Weather Observation Station 4 HackerRank Solution in SQL.

Problem

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

Field	Type
ID	NUMBER
CITY	VARCHAR2(21)
STATE	VARCHAR2(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.

Solution – Weather Observation Station 4 in SQL

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

Disclaimer: The above Problem (Weather Observation Station 4) is generated by Hacker Rank but the Solution is provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.