SQL SUM() Function – Calculate Totals in Your Data

Introduction – What is SQL SUM()?

The SUM() function in SQL is used to add together all values in a numeric column and return the total. It’s one of the core aggregate functions used in reports, analytics, and financial calculations.

In this guide, you’ll learn how to:

• Use SUM() in basic queries
• Apply SUM() with GROUP BY
• Filter aggregated results using HAVING
• Handle NULL values in SUM()

1. Basic SUM() Syntax

SELECT SUM(column_name) FROM table_name;

Adds all non-NULL numeric values from the specified column.

2. Example – Total Salaries

SELECT SUM(salary) AS total_salary
FROM employees;

Calculates the total sum of the salary column.

3. SUM() with GROUP BY

SELECT department, SUM(salary) AS dept_total
FROM employees
GROUP BY department;

Computes salary totals per department.

4. Filtering Aggregates with HAVING

SELECT department, SUM(sales) AS total_sales
FROM employees
GROUP BY department
HAVING SUM(sales) > 100000;

Filters groups where total sales exceed 100,000.

5. NULL Handling in SUM()

• SUM() ignores NULLs
• Use COALESCE() to treat NULLs as 0:

SELECT SUM(COALESCE(sales, 0)) FROM revenue;

Ensures NULL values do not affect the result.

Best Practices

Summary – Recap & Next Steps

The SQL SUM() function is a powerful tool for aggregating numeric data. From calculating revenue to summarizing totals per group, it provides fast and reliable summaries.

Key Takeaways:

• Use SUM(column) to calculate totals
• Combine with GROUP BY for segmented results
• Use HAVING to filter summarized totals
• Handle NULLs using COALESCE()

Real-World Relevance:
Common in financial reports, inventory tracking, KPI dashboards, and analytics queries.

FAQ – SQL SUM Function

What does SQL SUM() do?

It returns the total of all numeric (non-NULL) values in a column.

Does SUM() ignore NULL values?

Yes. Use COALESCE() to treat NULLs as zeros if needed.

Can I use SUM() with GROUP BY?

Absolutely! It’s one of the most common use cases.

How can I alias a SUM() result?

Use AS: SELECT SUM(sales) AS total_sales FROM orders;

Can I use SUM() in a subquery?

Yes. SUM() works inside subqueries, CTEs, and views.