In the auto shop examples in Section 9.2.2, what are some problems that might arise in Mario’s system? Why won’t Danica run into the same problems? Provide specific examples in your answer.

Question

What will be an ideal response?

Answer 1

Mario relies on two file-oriented systems, sometimes called file processing systems, to manage his business. The two systems store data in separate files that are not connected or linked, as shown in Figure 9-2. Unfortunately, using two separate systems means that some data is stored in two different places, and the data might or might not be consistent. For example, three data items (Mechanic No, Name, and Pay Rate) are stored in both files. This redundancy is a major disadvantage of file-oriented systems, because it threatens data quality and integrity. In fact, Figure 9-2 includes a typical discrepancy, which involves the pay rate for Jim Jones.
Danica, on the other hand, uses a database management system (DBMS) with two separate tables that are joined, so they act like one large table as shown in Figure 9-3. In Danica’s system, the tables are linked by the Mechanic No field, which connects the tables. Notice that except for the common field, no other data items are duplicated. The DBMS design, also called a relational database or relational model, was introduced in the 1970s and continues to be the dominant approach for organizing, storing, and managing business data. The error in Mario’s file could not occur in Danica’s relational database, because an employee’s pay rate is stored in only one place.