When working with databases, it is common to calculate the average of a set of values. In SQL, there are different ways to accomplish this task depending on the specific database you are using. In this article, we will compare the AVG function and the AVGIFS function in different databases.

SQL AVG Function

The AVG function in SQL is a built-in aggregate function that calculates the average of a column or expression. It takes all values within a specified column and returns the average value.

The general syntax of the AVG function is as follows:

SELECT AVG(column_name)
FROM table_name;

Let’s consider an example where we have a table named employees with a column salary:

SELECT AVG(salary)
FROM employees;

This query will return the average salary of all employees in the employees table.

Pros of AVG Function

• Simple Syntax: The AVG function has a straightforward syntax, making it easy to use.
• Wide Support: It is widely supported across different databases, including MySQL, PostgreSQL, Oracle, and SQL Server.

Cons of AVG Function

• No Conditional Filtering: The AVG function calculates the average of all values within the specified column, without the ability to filter based on conditions.

SQL AVGIFS Function

Some databases provide additional functions like AVGIFS to address the limitations of the AVG function. These functions allow for average calculations with conditional filtering.

Let’s compare how similar functionality is achieved in different databases:

MySQL

In MySQL, the AVG function can be combined with a WHERE clause to achieve conditional filtering. For example:

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

PostgreSQL

PostgreSQL provides the AVG function along with the FILTER clause, which allows for filtering based on conditions. For example:

SELECT AVG(salary)
FROM employees
WHERE department = 'Marketing'
GROUP BY department;

Oracle

Oracle’s AVG function can be used with a CASE statement to achieve conditional filtering. For example:

SELECT AVG(CASE WHEN department = 'Marketing' THEN salary END)
FROM employees;

SQL Server

In SQL Server, the AVG function can be combined with the WHERE clause to filter based on conditions. For example:

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

Pros of AVGIFS Functions

• Conditional Filtering: AVGIFS functions allow for calculating the average based on specified conditions.

Cons of AVGIFS Functions

• Database-Specific: The availability and syntax of AVGIFS functions may vary across different database systems.

Conclusion

In summary, the AVG function is a common SQL aggregate function that calculates the average of a column’s values. However, some databases offer additional functions like AVGIFS to enable conditional filtering while computing the average. The choice between AVG and AVGIFS depends on the specific database you are using and its supported functions.