This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Constraints”.
1. _____________ express the number of entities to which another entity can be associated via a relationship set.
a) Mapping Cardinality
b) Relational Cardinality
c) Participation Constraints
d) None of the mentioned
Explanation: Mapping cardinality is also called as cardinality ratio.
2. An entity in A is associated with at most one entity in B, and an entity in B is associated with at most one entity in A.This is called as
Explanation: Here one entity in one set is related to one one entity in other set.
3. An entity in A is associated with at most one entity in B. An entity in B, however, can be associated with any number (zero or more) of entities in A.
Explanation: Here more than one entity in one set is related to one one entity in other set.
4. Data integrity constraints are used to:
a) Control who is allowed access to the data
b) Ensure that duplicate records are not entered into the table
c) Improve the quality of data entered for a specific property
d) Prevent users from changing the values stored in the table
Explanation: The data entered will be in a particular cell (i.e., table column).
5. Establishing limits on allowable property values, and specifying a set of acceptable, predefined options that can be assigned to a property are examples of:
b) Data integrity constraints
c) Method constraints
d) Referential integrity constraints
Explanation: Only particular value satisfying the constraints are entered in the column.
6. Which of the following can be addressed by enforcing a referential integrity constraint?
a) All phone numbers must include the area code
b) Certain fields are required (such as the email address, or phone number) before the record is accepted
c) Information on the customer must be known before anything can be sold to that customer
d) Then entering an order quantity, the user must input a number and not some text (i.e., 12 rather than ‘a dozen’)
7. ______ is a special type of integrity constraint that relates two relations & maintains consistency across the relations.
a) Entity Integrity Constraints
b) Referential Integrity Constraints
c) Domain Integrity Constraints
d) Domain Constraints
8. Which one of the following uniquely identifies the elements in the relation?
a) Secondary Key
b) Primary key
c) Foreign key
d) Composite key
Explanation: Primary key checks for not null and uniqueness constraint.
9. Drop Table cannot be used to drop a table referenced by a _________ constraint.
a) Local Key
b) Primary Key
c) Composite Key
d) Foreign Key
Explanation: Foreign key is used when primary key of one relation is used in another relation.
10. ____________ is preferred method for enforcing data integrity
b) Stored Procedure
Explanation: Constraints are specified to restrict entries in the relation.
Sanfoundry Global Education & Learning Series – Database Management System.