Objective: 🔍 Goal: Master the art of summarizing and grouping your data using aggregate functions in SQL, such as SUM, COUNT, AVG, MAX, MIN, and the GROUP BY clause.

Introduction: 💡 Ever wondered how e-commerce platforms quickly calculate the total sales for a particular product, or how forums determine the number of posts a user has made? Aggregate functions in SQL are the heroes behind the scenes, performing these operations in milliseconds.

Main Content:

1️⃣ SUM Function:

• Concept: The SUM function allows you to add up all the values in a specific column, providing a total.
• Sample Question: "What's the total sales amount from the order table?"
• Example:

SELECT SUM(total_amount) as total_amount FROM orders;

2️⃣ COUNT Function:

• Concept: With the COUNT function, you can determine how many rows match a certain condition or just count all rows in a table
• Sample Question: "How many products are currently in our inventory?"
• Example:

SELECT COUNT(product_id) as number_of_products FROM products;

2️⃣ COUNT DISTINCT:

• Concept: The DISTINCT keyword in SQL is used to return only distinct (unique) values in the result set of a SELECT statement. It eliminates any duplicate records based on the columns specified. It's particularly useful when you want to know the unique values of a column or set of columns in a table.
• Sample Question: "How many unique categories do we have in our product inventory?"