What are the various situations in which an attribute can use a null value?
Database Management System > DBMS Data Models > ER Diagrams
4441
Answer:
There are various situations in which an attribute can use a NULL value. One such situation is when a particular entity does not have an appropriate value for an attribute. In such a situation, the attribute takes a special value called the NULL value. A null value of an attribute may indicate "not applicable". For example, consider an entity type PERSON with three attributes First_name, Middle_name and Last_name. Since not every person has a middle name, the person without any middle name will have a NULL value for the attribute Middle_name. Another situation when the NULL value is used is when the value of a particular attribute is unknown. An unknown category can further be classified as missing and not known. For example, if the attribute Book_title has the value NULL, it indicates that the title of the book is missing, as every book must have a title. However, if the attribute Phone has a NULL value, it indicates that it is not known whether the value for Phone exists or not.
This Particular section is dedicated to Question & Answer only. If you want learn more about Database Management System. Then you can visit below links to get more depth on this subject.
Join Our telegram group to ask Questions
Click below button to join our groups.