CS Free MCQ Bank

[ Option A ]

In India, each person has only one Aadhaar Card, and each Aadhaar number belongs to only one person.

• Each person can possess only one unique Aadhaar Card.
• Each Aadhaar Card corresponds to exactly one person.

This is a One-to-One (1:1) relationship in the ER Model.

[ Option C ]

A derived attribute is an attribute whose value can be calculated from other stored attributes.

• Age can be derived from Date of Birth.
• Year of services can be derived from Date of Joining.

[ Option A ]

A composite attribute is an attribute that can be divided into smaller sub-attributes.
Address can be broken into House No, Street, City, State, and PIN Code, so it is a composite attribute.
Age, City and State are the simple attributes and cannot be meaningfully divided further.

[ Option B ]

Generalization is a bottom-up approach where lower-level entities are combined to form a higher-level, more general entity. 

• For example, combining Student and Teacher into a general entity Person.

Specialization is a top-down approach, where a higher-level entity is divided into lower-level entities. 

• For example, Employee is a general entity. It is specialized into Teaching_Employee and Non_Teaching_Employee based on the type of work. This is called specialization because we move from general to specific.

[ Option A ]

E-R modeling is primarily a Top-Down approach to database design. It starts with identifying high-level entities and relationships in the real world and then gradually breaks them down into attributes and detailed structures.

[ Option D ]

In an ER (Entity–Relationship) Model, an attribute is a property or characteristic of an entity. It tells us something about the entity. Attributes describe the entity with the help of values.
For example, for entity Employee the Name, Age, Salary, Skills and for entity Student the Roll No, Course, Address are attributes.

• Attributes help us store meaningful and organized information about each entity in the system.

Types of Attributes:

Because an employee can have multiple skills, and ER models represent such attributes as Multivalued Attributes.

[ Option A ]

A composite attribute is an attribute that can be divided into smaller sub-attributes.
The attribute Name can be broken into First Name, Middle Name, and Last Name, so it is a composite attribute.
Age, City and State are simple attribute and cannot be meaningfully divided further.

[ Option A ]

In an ER diagram, a Weak Entity Set cannot be uniquely identified by its own attributes and relies on a Strong (Identifying) Entity Set for uniqueness. The relationship that connects a weak entity to its identifying strong entity is known as the identifying relationship. This relationship is depicted using a Double Diamond symbol.

Since every weak entity must be associated with a strong entity, there is Total Participation, which is represented by Double Lines connecting the weak entity set to the identifying relationship.

[ Option C ]

In an E–R diagram, different shapes are used to represent different components:

• A rectangle represents an entity set like Student, Employee, Course.
• An oval represents an attribute.
• A diamond represents a relationship between entity sets.

OTHER NOTATION:

[ Option C ]

An ER (Entity-Relationship) Model is used to visually represent the structure of a database.

• It shows entities, attributes, and relationships.
• It focuses on what data is stored and how it is related, without worrying about how it is physically stored.

This type of representation corresponds to the Conceptual Schema of a database.

[ Option C ]

In an E–R diagram, a double ellipse or double oval is used to represent a multivalued attribute, which means an attribute that can have more than one value for a single entity. For example, a person can have multiple phone numbers, so Phone_Number is shown using a double ellipse.

[ Option A ]

An entity in a database or data modeling context is a real-world object or concept that can be uniquely identified and about which data can be stored.
Entities are represented by a set of attributes, which describe the characteristics or properties of that entity. For example, a Student entity may have attributes like Rollno, Name, Class, Age, and Address. These attributes provide information about the entity and are used to uniquely distinguish one entity instance from another.

[ Option C ]

In an Entity-Relationship (E-R) model, a relationship represents an association among two or more entities. It shows how entities are connected to each other.

[ Option C ]

In an Entity-Relationship (ER) Diagram, Total Participation means that every entity in an entity set must participate in a given relationship.

To represent this, we use a Double Line between the entity set and the relationship set. This indicates that the participation of the entity is mandatory or required or total.