31: Which term describes the management of simultaneous transactions to prevent conflicts? A.Parallelism B.Serialization C.Database control D.Concurrency control Correct Answers: D

21: Consider the Information Engineering diagram shown in the exhibit for a building management company. Referential integrity must be maintained such that a building cannot be deleted when it has residents. Building_ID, R_ID, Room_Count and Room_Num are integer numbers, whereas Bldg_Name, Location and Res_Name are all represented by variable-length strings with a maximum of 20 […]

11: Which of the following ACID properties requires that a transaction be executed in its entirety or not all? A.Durability B.Consistency C.Isolation D.Atomicity Correct Answers: D

1: Which term describes the rejoining of relations that have been decomposed? A.Normalization B.Denormalization C.Referential integrity D.Domain constraints Correct Answers: B

31: What is a virtual table? A.A virtual table is a relation created as the result of data manipulation, and is not a permanent part of the database. B.A virtual table is a relation stored in the databases memory; it is used when multiple users access the same relation in a database. C.A virtual table […]

21: Which term best defines a database system in which data records are stored with no structured relationships between the records? A.Flat-file database B.Relational database C.Distributed database D.Object-oriented database Correct Answers: A

11: Which relational algebraic operation is used to select specific columns (attributes) from a relation? A.Union B.Difference C.Projection D.Intersection Correct Answers: C

1: Consider the following relations shown in the exhibit. Which of the following SQL statements would return the Customers2 relation from the Customers relation?