Database Management System MCQs with Answers
Practice important Database Management System MCQs with answers and explanations.
Multiple Choice Questions
Q171: Which of the following is an example of a supertype/subtype relationship?
- A: EMPLOYEE being divided into SALARIED and HOURLY employees
- B: TRUCK being classified into different models
- C: VEHICLE being categorized by color
- D: PRODUCT being listed by different categories
View Answer
A
Q172: What does a total completeness constraint ensure?
- A: All instances of a supertype must be represented in at least one subtype
- B: No instances of a supertype need to be represented in any subtype
- C: Partial representation of the supertype instances is acceptable
- D: No subtypes are required for the supertype
View Answer
A
Q173: What is the disjointness constraint in database systems?
- A: It restricts a supertype entity instance to only one subtype entity instance at a time
- B: Allows a supertype entity instance to be associated with multiple subtype instances
- C: Permits multiple instances of subtypes for a single supertype instance
- D: Requires that all subtype instances are included in the supertype
View Answer
A
Q174: The overlap rule permits:
- A: A supertype instance to exist in multiple subtype instances at once
- B: A supertype instance to exist in only one subtype instance
- C: Disjointness between a supertype and its subtypes
- D: Partial completeness in subtype relationships
View Answer
A
Q175: What does the subtype discriminator help determine?
- A: The specific subtype to which a supertype instance belongs
- B: Whether a supertype instance is valid for database storage
- C: How attributes are inherited from subtypes
- D: Which attributes are common to all subtypes
View Answer
A
Q176: In the example of vehicles, what is the partial completeness constraint?
- A: Only a few types of vehicles are stored in the vehicle entity, ignoring others
- B: All vehicle types are stored, including those not explicitly mentioned
- C: A complete representation of all vehicle types in the system
- D: All vehicle data must be stored in separate subtypes
View Answer
B
Q177: Fill in the blank: The process of creating different types of sub entities from a supertype entity is supported by the __________ of the designer about the organization.
- A: knowledge
- B: relationships
- C: data
- D: storage
View Answer
B
Q178: The complete disjoint constraint means:
- A: A supertype instance can be associated with only one subtype at a time
- B: Multiple subtype instances can be associated with a single supertype instance
- C: Partial representation of subtypes is acceptable
- D: All subtype instances must be present for every supertype instance
View Answer
A
Q179: Which rule specifies that a supertype entity instance can be present in multiple subtypes?
- A: Overlap rule
- B: Disjointness rule
- C: Partial disjoint rule
- D: Complete disjoint rule
View Answer
A
Q180: Fill in the blank: In an overlapping constraint, a part that is manufactured and purchased can be represented in the __________ entity subtypes.
- A: both
- B: none
- C: one
- D: neither
View Answer
A