➗ 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

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✅ 1. Basic AVG() Syntax

SELECT AVG(column_name) FROM table_name;

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

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💰 2. Example – Average Salary

SELECT AVG(salary) AS average_salary
FROM employees;

✅ Calculates the average salary of all employees.

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📊 3. AVG() with GROUP BY

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

✅ Shows the average salary per department.

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🔍 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.

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📉 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.

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📘 Best Practices

✅ Do This	❌ Avoid This
Use aliases for readable output	Leaving unnamed aggregate results
Pair with GROUP BY for analysis	Averaging raw rows without context
Use COALESCE() for NULL handling	Assuming NULLs are counted as 0

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📌 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.

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❓ 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;

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