Aggregate: Count Users Per Country

SQL

Technical Specification

Write a query to count how many users are there in each country.

Input/Output Samples

Input:users

Output:{ country:'India', user_count:120 } etc.

Optimal Logic Path

SELECT 
  country,
  COUNT(*) AS user_count
FROM users
GROUP BY country;

Architectural Deep-Dive

GROUP BY groups rows by country so aggregate functions like COUNT work per group.