Answer: Metadata is data about the structure of the database itself. This includes data about the names of all the tables in the database, the names of all the columns in each of the tables, the data type of each column in each table, the properties of the tables and the columns, etc. Metadata accounts for the "self-describing" aspect of the definition of a database as a "self-describing collection of integrated tables."
Diff: 2 Page Ref: 19
AACSB: Information Technology
Chapter Obj.: Know the components of a database system
Classification: Concept
76) Briefly describe the function of the DBMS in a database system.
Answer: The DBMS creates the database and the tables and structures within it. The DBMS also reads and updates the database data. It receives requests from application programs to perform data maintenance tasks. These requests are translated into actions that are performed on the database. In addition to maintaining the user data within the database, the DBMS also maintains the database structures. The DBMS also enforces any rules that have been defined to govern the values of the data, such as data type requirements and referential integrity constraints. The DBMS controls concurrency issues, which deal with the unwanted interruption of one user's work by another user's work. As the only point of entry into the database, the DBMS also provides security for the database to restrict users' access to only the data that they have authority to read or modify. Finally, the DBMS is responsible for the creation of backup copies of the database data and for restoring the database in case a recovery is required.
Diff: 2 Page Ref: 20
AACSB: Information Technology
Chapter Obj.: Learn the purpose of a database management system (DBMS)
Classification: Concept
77) What are "referential integrity constraints"? Give an example.
Answer: A referential integrity constraint is a rule that restricts certain actions on the database data. A referential integrity constraint is used to ensure that the values in a field in one table have matching values in a corresponding field in another table. These constraints are enforced by the DBMS, which will not allow changes to the values of the database that would result in violations of this rule. For example, a database has an EMPLOYEE table and a VEHICLE table that are used to store data on employees and the vehicles that they are assigned to drive. The EMPLOYEE table has a column called EmployeeID that is used to distinguish one employee record from another. The VEHICLE table also has an EmployeeID column that is used to associate a vehicle with the appropriate employee. A referential integrity constraint could be used to prevent a vehicle from being assigned to an employee with an EmployeeID that does not appear in the EMPLOYEE table by requiring that all values in EmployeeID in the VEHICLE table have a matching value in EmployeeID in the EMPLOYEE table.
Diff: 3 Page Ref: 20
AACSB: Information Technology
Chapter Obj.: Learn the purpose of a database management system (DBMS)
Classification: Concept
78) Briefly describe the function of an application program in a database system.
Answer: The application program is responsible for creating and processing forms. The application displays the form to the user, allows the user to complete the data entry, evaluates the form to determine which data management tasks need to be performed, and transmits the appropriate requests to the DBMS. The application creates and transmits queries. The queries are requests for data that are created in a language like SQL, and transmitted to the DBMS to have the requested data returned to the application program. The application also creates and processes reports. The query to retrieve the necessary data for the report is sent to the DBMS. When the DBMS returns the needed data, the application manipulates it as necessary to create the requested report. The application program also applies application logic to control the manipulation of data in accordance with the business rules. Finally, the application program is responsible for providing control. Control must be exercised to allow the users to make choices for functions and tasks as appropriate for their jobs. Also, control must be exercised to manage the activities of the DBMS.
Diff: 2 Page Ref: 20-23
AACSB: Information Technology
Chapter Obj.: Learn the purpose of a database management system (DBMS)
Classification: Concept
79) What are the advantages and disadvantages of personal DBMS products hiding the complexity of database systems?
Answer: The advantage of hiding the complexity of database systems is that it makes database systems easier for novices to create. Using the graphical tools and wizards of a desktop DBMS product, databases and application programs can be created without developing much database expertise. The disadvantage of hiding the complexity is that the developer does not understand what the desktop DBMS product is doing on the developer's behalf. This limits the developer's ability to create systems with functions not anticipated by the DBMS design team. Further, the developer is limited in their ability to develop systems on a larger scale.