AVG() in PostgreSQL

The AVG() function in PostgreSQL calculates the average (mean) value of a numeric column.

Syntax

SELECT AVG(column_name) FROM table_name WHERE condition;

1. Calculating the Average of a Column

SELECT AVG(salary) FROM employees;

✅ Returns the average salary of all employees.

2. Using AVG() with a WHERE Condition

SELECT AVG(salary) FROM employees WHERE department = 'IT';

✅ Returns the average salary of employees in the IT department.

3. Using AVG() with GROUP BY

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

✅ Returns the average salary for each department.

4. Using ROUND() to Format the Result

By default, AVG() returns a decimal value. You can round it to a specific number of decimal places:

SELECT ROUND(AVG(salary), 2) FROM employees;

✅ Returns the average salary rounded to 2 decimal places.

5. Handling NULL Values in AVG()

• AVG() ignores NULL values in calculations.
• If all values are NULL, it returns NULL.

Example:

SELECT AVG(bonus) FROM employees;

✅ If some employees don’t have a bonus (NULL), they are not included in the calculation.