Problem 1
What is the significance of database management systems?
Problem 2
What is a database model?
Problem 3
What is a lossless decomposition or a nonloss decomposition?
Problem 5
Identify two benefits of separating application software from the DBMS.
Problem 7
Identify the level within a database system (user, programmer of application software, designer of the DBMS software) at which each of the following concerns or activities occur: a. How should data be stored on a disk to maximize efficiency? b. Is there a vacancy on flight 243 ? c. How should a relation be organized in mass storage? d. How many times should a user be allowed to mistype a password before the conversation is terminated? c. How can the PROJECT operation be implemented?
Problem 8
Which of the following tasks are handled by a DBMS? a. Ensure that a user's access to the database is restricted to the appropriate subschema. b. Translate commands stated in terms of the database model into actions compatible with the actual data storage system. c. Disguise the fact that the data in the database is actually scattered among many computers in a network.
Problem 9
Describe how the following information about railways, trains (for a particular day), and passengers would be represented in a relational database: Trains: Rolar, Omni, and Holiday Trains for Rolar: R221, R567, and R234 Holiday special Trains: H897 and H008 Trains for Omni: O999 and O815 John has reservations on R221 (scat 34U), R567 (seat 23U), and R234 (seat 43L). Henry has reservations on O999 (seat 15L) and \(\mathrm{HOO8}\) (seat 18L). Duke has reservations on H897 (seat 7U) and O815 (seat 2L).
Problem 10
To what extent is the order in which SELECT and PROJECT operations are applied to a relation significant? That is, under what conditions will SELECTing and then PROJECTing produce the same results as first PRDJECTing and then SELECTing?
Problem 18
Design a relational database containing information about students, their courses, and their current semester along with their disciplines. (Avoid redundancies similar to those in Figure 9.4.)
Problem 21
Design a relational database containing information about parts, suppliers, and customers. Each part might be supplied by several suppliers and ordered by many customers. Each supplier might supply many parts and have many customers. Each customer might order many parts from many suppliers; in fact, the same part might be ordered from more than one supplier. (Avoid redundancies similar to those in Figure 9.4.)
