We use NVL and NVL2 functions to check if a value is NULL or not. Both these functions can be replaced with DECODE or CASE statements.
In NVL(item_to_check, alternate_value) function there are two arguments. If item_to_check is null then alternate_value is returned. If item_to_check is not null, then item_to_check is returned.
In NVL2(item_to_check, alternate_value1, alternate_value2) function there are three arguments. If item_to_check is null then alternate_value2 is returned. If item_to_check is not null, then alternate_value1 is returned. It is a short IF then ELSE statement.Read the full book at www.amazon.com