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Core Code Modern Dev Handbook

SQL Avg

AVG() returns the average value of a numeric column. Learn how to calculate averages and use grouping and rounding.
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SQL AVG Function

The AVG() function returns the average (mean) value of a numeric column. It is commonly used for reporting and analysis.

Basic Syntax

SELECT AVG(column_name)
FROM table_name;

Example: Average Price

SELECT AVG(price) AS average_price
FROM products;

Using AVG with WHERE

You can filter rows before calculating the average.

SELECT AVG(price) AS average_electronics_price
FROM products
WHERE category = 'Electronics';

Using AVG with GROUP BY

To calculate averages per category or group, combine AVG with GROUP BY.

SELECT category,
       AVG(price) AS average_price
FROM products
GROUP BY category
ORDER BY average_price DESC;

Using AVG with Expressions

You can calculate averages based on computed values.

SELECT AVG(price * quantity) AS average_order_value
FROM order_items;

Rounding Results

Database systems often allow rounding numeric results for better presentation.

SELECT ROUND(AVG(price), 2) AS rounded_average_price
FROM products;

NULL Behavior

AVG() ignores NULL values. If all values are NULL, the result will be NULL.

Common Mistakes

  • Using AVG on non-numeric columns
  • Forgetting GROUP BY when selecting additional columns
  • Not handling NULL values properly

Next Step

Continue with SQL LIKE to learn how to search for patterns in text fields.

SQL Like →