List the various cases where the use of a null value would b

List the various cases where the use of a null value would be appropriate.

Solution

Null value would be applicable when a particular entity does not have an applicable value for an attribute. There are two cases for such situations. The first case arises when it is known that the attribute value exists but is missing. An example for cases like such would be if the Height attribute of a person is listed as null. The second case arises when it is not known whether the attribute value exists. An example would be is the HomePhone attribute of a person is null. in these two cases the null value would be appropriate