NVL

Oracle

NVL(expr1, expr2);

• expr1: This is the value to test. It is the source column or expression that may contain a NULL.
• expr2: This is the substitute value. If expr1 is determined to be NULL, then NVL function will return expr2 instead.

Example

SELECT NVL(column_name, 'N/A') FROM table_name;

Output

N/A

Explanation

This code snippet represents an example of using NVL() function in Oracle SQL. If the value in column_name is null, it will return ‘N/A’. Otherwise, the actual value in the column will be returned.

SQL Server

ISNULL( check_expression , replacement_value )

• check_expression: This is the expression to be checked for NULL. It can be of any type.
• replacement_value: This is the value to return if the check_expression is NULL. The replacement value must be of a type that is implicitly convertible to the type of the check_expression.

Example

SELECT ISNULL(NULL, 'Default Value');

Output

Default Value

Explanation

The NVL (or ISNULL in SQL Server) function is used to replace NULL values with a specified value. In the above example, the function checks the first argument (NULL) and since it is NULL, it returns the second argument (‘Default Value’).