Business Analyst: What is a SQL aggregate function?

Aggregate function — performs calculation on multiple rows.

Functions:

• COUNT() — number of rows.
• SUM() — total of values.
• AVG() — average.
• MIN() — smallest value.
• MAX() — largest value.

Example:

1-- Total orders
2SELECT COUNT(*) FROM orders;
3
4-- Average order amount
5SELECT AVG(amount) FROM orders;
6
7-- Total sales by customer
8SELECT customer_id, SUM(amount) as total
9FROM orders
10GROUP BY customer_id
11ORDER BY total DESC;

BA use:

• Summarize data.
• Calculate KPIs.
• Generate reports.