Today, let's move to the next topic of SQL Roadmap:

✅ Basic SQL Queries: Aggregations and GROUP BY

• Why aggregations matter
• Raw rows hide patterns
• Businesses care about totals, averages, counts
• Aggregations turn rows into answers

• Common aggregate functions
• COUNT: counts rows
• SUM: adds values
• AVG: finds average
• MIN: finds smallest value
• MAX: finds largest value

• Examples
SELECT COUNT(*) FROM orders;  -- total orders 
SELECT SUM(amount) FROM orders;  -- total revenue 
SELECT AVG(amount) FROM orders;  -- average order value 
SELECT MIN(amount), MAX(amount) FROM orders;  -- spend range 

• GROUP BY
• Groups rows by a column
• Applies aggregation per group
• One result per group
SELECT customer_id, SUM(amount) FROM orders GROUP BY customer_id;  -- total spend per customer 
SELECT order_date, COUNT(*) FROM orders GROUP BY order_date;  -- daily order volume 

• Important rule
Every column in SELECT must be aggregated or present in GROUP BY.

• Using WHERE with GROUP BY
SELECT customer_id, SUM(amount) FROM orders
WHERE amount > 5000
GROUP BY customer_id;  -- high-value orders per customer 

Real business use:
• Revenue per customer
• Orders per day
• Average order value per city

SQL Roadmap: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v/1615

Double Tap ♥️ For More