NVL Function in Oracle/PLSQL

The NVL function is used to replace NULL values by another value. Whenver a NULL value is encountered NVL replaces it by another value.

Syntax

NVL (expression 1, expression 2)

or

NVL ( string1, replace_with )

where string1 is the string which is tested for the NULL value and replace_with is the value which will be returned if the string is found to be NULL.

Example

select NVL(product_descr, product_name) from products;

In the above example if product_name is returned if the product_descr is found to be NULL else the value of product_descr is returned by the statement.

select NVL(salary, 0) from employees;
Here if the salary is found to be NULL then zero will be returned.