What is the meaning of the NVL function in Oracle?

In Oracle, the NVL function is used to handle NULL values. It takes two parameters, returning the value of the second parameter if the first parameter is NULL, and the value of the first parameter if it is not NULL.

The purpose of the NVL function is to replace NULL values, making it easier to manage NULL values in calculations and comparisons. By using the NVL function, it ensures that errors or uncertainties caused by NULL values are avoided in calculations and comparisons, and allows for the return of a non-NULL value as needed.

For example, consider a table containing students’ grades, where some rows have NULL grades. To calculate the average grade, you can use the NVL function to replace NULL values with 0, ensuring they do not affect the calculations.

Find the average grade of students, considering any null values as 0, from the student table.