Final answer:
The COALESCE function is used to handle NULL values in a database, providing alternative values instead of NULL. The IS NULL and IS NOT NULL operators also allow performing actions depending on whether a column contains NULL values.
Step-by-step explanation:
The COALESCE function allows different actions to be performed based upon whether a NULL value exists in a specified column. For example, in SQL, if you want to select a replacement value when there is a NULL in any column of your table, you could use the COALESCE function to specify what value should be displayed instead of NULL. It's often used in database querying and management to provide default values for displaying data in applications.
Furthermore, the IS NULL and related IS NOT NULL conditional operators are also commonly used to check for NULL values directly in the WHERE clause of an SQL statement, allowing for different actions or query results depending on the presence of NULLs.