Final answer:
The NVL and NVL2 functions in databases are used to handle null values. NVL replaces null values with a specified value, while NVL2 allows you to specify two different values based on whether the expression is null or not.
Step-by-step explanation:
The NVL and NVL2 functions in databases are used to handle null values. The main difference between the two functions is their behavior when dealing with null values.
NVL: The NVL function replaces a null value with another specified value. For example, if you use NVL(column_name, 'Unknown'), it will replace null values in the column with the string 'Unknown'.
NVL2: The NVL2 function allows you to specify two different values based on whether the evaluated expression is null or not. For example, if you use NVL2(column_name, 'Not Null', 'Null'), it will return 'Not Null' if the column value is not null, and 'Null' if it is null.