SQL AVG() Function – Calculate Averages in SQL

Introduction – What is SQL AVG()?

The AVG() function in SQL is used to calculate the average (arithmetic mean) of values in a numeric column. It’s ideal for understanding trends, measuring performance, and generating insights from data.

In this guide, you’ll learn how to:

• Use AVG() in queries
• Combine AVG() with GROUP BY
• Filter averages using HAVING
• Handle NULL values correctly

1. Basic AVG() Syntax

SELECT AVG(column_name) FROM table_name;

Returns the average of all non-NULL numeric values in the specified column.

2. Example – Average Salary

SELECT AVG(salary) AS average_salary
FROM employees;

Calculates the average salary of all employees.

3. AVG() with GROUP BY

SELECT department, AVG(salary) AS avg_salary
FROM employees
GROUP BY department;

Shows the average salary per department.

4. Filtering AVG() with HAVING

SELECT department, AVG(salary) AS avg_salary
FROM employees
GROUP BY department
HAVING AVG(salary) > 60000;

Filters groups to only include departments with an average salary above 60,000.

5. NULL Handling in AVG()

• AVG() ignores NULLs automatically
• Use COALESCE() to treat NULLs as zero:

SELECT AVG(COALESCE(sales, 0)) FROM performance;

Ensures a value is included even if some rows are missing data.

Best Practices

Summary – Recap & Next Steps

The SQL AVG() function is essential for calculating average metrics in datasets. From salary trends to product ratings, AVG() gives you reliable arithmetic means.

Key Takeaways:

• Use AVG(column) to compute average values
• Pair with GROUP BY for segmented insights
• Use HAVING to filter based on averages
• Handle NULLs using COALESCE() if needed

Real-World Relevance:
Used in performance analytics, rating systems, market analysis, and sales reporting.

Next: Explore MIN() and MAX() to find range boundaries.

FAQ – SQL AVG Function

What does SQL AVG() do?

It returns the arithmetic mean of all non-NULL values in a numeric column.

Does AVG() ignore NULLs?

Yes. Only non-NULL values are considered.

How do I get average per group?

Use GROUP BY. Example:

SELECT city, AVG(price) FROM hotels GROUP BY city;

Can I filter average values?

Yes. Use HAVING to filter on aggregate values.

Can AVG() work with expressions?

Yes. Example:

SELECT AVG(score * 1.5) FROM reviews;