Answer to Question #295729 in Accounting for Jen

Question

The relational database is the technology basis of accounting information systems. Because the database management system can store and access data very fast and manage internal controls by assigning access control rights. The fast data availability makes many real-time AI applications achievable. You can see the root links between any data-related emerging technologies and relational databases. This chapter teaches you the primary working mechanism of relational databases. MS Access will be used to demonstrate hands-on practicing. Basic concepts in relational databases. What a database is and why it is important. The concepts of the data schema, primary key, and foreign key.

Question 1: The the primary key cannot be null in the relational database design. Please use one or two sentences to explain why?

Answer 1

NULL is a unique marker used to represent a missing value. When it is used, it shows the absence of a value in the database. It represents an unknown value in a relational database. 

A primary key uniquely identifies tuples in a table hence, it cannot be Null. A primary key is selected to be used as a mechanism to identify the whole entity set, thus must contain a value and cannot be Null. In a relational database, primary key fields are used for instance, in an access database as unique identifiers for every field hence cannot be Null.