SQL Aggregate Functions: Stop Guessing, Start Calculating

SQL Aggregate Functions: Stop Guessing, Start Calculating If you've ever needed to answer questions like "How many orders did we get this month?", "What's our total revenue?", or "Who's our highest-paid employee?" — you need SQL aggregate functions. They're the workhorses of data analysis, and once you understand them, you'll wonder how you ever got by without them. In this guide, we'll cover the five essential SQL aggregate functions — COUNT , SUM , AVG , MIN , and MAX — with realistic examples you can actually use in your projects. What Are Aggregate Functions? Aggregate functions take a group of rows and return a single value. Instead of seeing one result per row, you get a summary. Think of them as the SQL equivalent of a calculator that works across your entire dataset. We'll use a sample orders table throughout this article: CREATE TABLE orders ( order_id INT PRIMARY KEY , customer_id INT , product_name VARCHAR ( 100 ), quantity INT , unit_price DECIMAL ( 10 , 2 ), order_date DAT