AVG Function - SQL

Overview

The AVG function in SQL calculates the average value of a numeric column in a database table. It is commonly used in SELECT statements to aggregate data, providing a mean value for specified columns.

Example:

SELECT AVG(salary)
FROM company.employees
WHERE department_id = 1

Syntax:

SELECT AVG(column_name)
FROM table_name
[WHERE condition]

This calculates the average of the values in column_name from table_name that meet the specified condition. In this syntax, the WHERE Statement is optional, if omitted then the AVG function will calculate the average for all rows in the table.

Sample Data:

    
            department_id
            salary
        
            3
            123000
        
            2
            135000
        
            3
            115000
        
            NULL
            115000
        
            2
            125000
        
            1
            120000
        
            1
            105000
        
            5
            200000
        
            2
            107000
        
            1
            100000

department_id	salary
3	123000
2	135000
3	115000
NULL	115000
2	125000
1	120000
1	105000
5	200000
2	107000
1	100000

Example: Without the WHERE Statement

In this example, we are taking the average of the salary column in the company.employees table. The final result is an average of 127,000.

Example: With the WHERE Statement

In this example, we are taking the average of the salary column in the company.employees table where the department_id column equals 1. The final result is an average of 108,333.33.