SQL Count unique data by using count() and DISTINCT

Author: Al-mamun Sarkar Date: 2020-03-27 19:58:30

Query the difference between all cities and all unique cities from the STATION table. This is the solution of HackerRank's Weather Observation Station 4 SQL problem.

Table name: STATION

Table Structure:

Fileds Type
ID NUMBER
CITY VARCHAR
STATE VARCHAR
LAT_N NUMBER
LONG_W NUMBER

 

SQL Query:

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