This set of RDBMS Multiple Choice Questions & Answers (MCQs) focuses on “Database Design Process”.
1. Which of the following is not a process of generating a good relational schema?
a) Converting ER diagrams to relational schema
b) Decomposing the relational schema while satisfying functional dependencies
c) Joining multiple relations together to form a single relation containing all the attributes
d) A design of relations which is then tested and modified to satisfy given normal forms
View Answer
Explanation: Joining multiple relations together to form a single relation containing all the attributes is not a method for the development of good relational schema because it might violate the normal forms if it is combined.
2. What is unique role assumption?
a) The attribute name has a unique meaning in the database
b) The attributes are all unique
c) No two tuples have even a single same value in a relation
d) None of the mentioned
View Answer
Explanation: Unique role assumption means that the attribute names must have unique meaning in the database. This prevents us from using the same attribute to mean different things in different schemas.
3. The process of making a normalized schema unnormalized is called as _________
a) Unnormalization
b) Denormalization
c) Renormalization
d) Annormalization
View Answer
Explanation: The process of making a normalized schema unnormalized is called as denormalization. Designers use it to tune performance of systems to support time-critical operations.
4. State true or false: Crosstabs are not desirable in a database design
a) True
b) False
View Answer
Explanation: Crosstabs may be useful for the users but they are not desirable in a database system because the queries would get more complicated due to the addition of cross tabs.
5. The data that have a time interval associated with them during which they are valid are called as ________
a) Timed data
b) Temporal data
c) Model data
d) Clocked data
View Answer
Explanation: The data that have a time interval associated with them during which they are valid are called as Temporal data. We use the term snapshot to mean the value of the data at a particular point in time.
6. The value of the data at a particular time is called as?
a) Instance
b) Picture
c) Snapshot
d) None of the mentioned
View Answer
Explanation: The value of the data at a particular time is called as a snapshot. This is used in temporal data.
7. Functional dependencies that have a time associated with them during which they are valid are called as________
a) Timed functional dependencies
b) Clocked functional dependencies
c) Temporal functional dependencies
d) Modeled functional dependencies
View Answer
Explanation: Functional dependencies that have a time associated with them during which they are valid are called as temporal functional dependencies. All snapshots of the relation should satisfy the functional dependency for it to be a temporal functional dependency.
8. State true or false: Overlapping time intervals cannot be prevented
a) True
b) False
View Answer
Explanation: IF a system supports a native valid time type, then the system can detect and prevent overlapping time intervals.
9. Which of the following is the time of temporal data that record when a fact was recorded in a database?
a) Transaction time
b) Valid time
c) Enter time
d) Exit time
View Answer
Explanation: The transaction time is the time of temporal data that records when a fact was recorded in a database.
10. To specify the foreign keys in relations referencing temporal data we need to specify _______
a) The time interval
b) The Boolean value for the working
c) The integer corresponding to the relation number
d) None of the mentioned
View Answer
Explanation: To specify the foreign keys in relations referencing temporal data we need to specify the time interval. The time interval specification thus preserves referential integrity in the relation.
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