PostgreSQL — Group By

Basic Group By

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

Multiple Columns

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

With Aggregate Functions

SELECT 
    country,
    COUNT(*) as user_count,
    AVG(age) as avg_age
FROM users 
GROUP BY country;

Having

SELECT country, COUNT(*) 
FROM users 
GROUP BY country 
HAVING COUNT(*) > 10;

Group By All

SELECT * FROM users GROUP BY ALL;

Mini Practice

1. Group by single column
2. Group by multiple columns
3. Use aggregate functions
4. Filter with HAVING

Up Next

Continue with Having — filtering groups.