Quiz # 2 (Chapter 3 & 4)

Each simple attribute of an entity type is associated with a domain, which specifies the set of values that may be assigned to that attribute for each individual entity. The domain defines the range or type of values that are allowed for a particular attribute. The value set refers to the actual set of values that are valid for the attribute within the defined domain.

A key attribute is an attribute that has distinct values for each individual entity in the entity set. It is used to uniquely identify each entity in the set.

The degree of a relationship refers to the number of entities involved in it. In other words, it indicates the number of entities that participate in a particular relationship. The more entities involved, the higher the degree of the relationship.

The correct answer is "Domain". In the context of entity types, each simple attribute is associated with a value set, which specifies the set of values that can be assigned to that attribute for each individual entity. This value set is called the domain. The domain defines the range of valid values for an attribute and helps enforce data integrity by restricting the values that can be assigned to the attribute.

An atomic attribute is a single attribute that cannot be divided further and has only one meaning. It represents a single piece of information about an entity or a relationship. Unlike composite attributes, which are made up of multiple sub-attributes, atomic attributes are indivisible and cannot be broken down into smaller components. Therefore, the correct answer is atomic attribute.

If an attribute has different number of values for each entity, it will be modeled as multivalued. This means that the attribute can have multiple values for a single entity. For example, if we have an attribute called "phone number" and some entities have one phone number while others have multiple phone numbers, then this attribute would be considered multivalued.

The ER model represents the basic object as an entity. In the ER model, an entity is a real-world object or concept that has attributes and can be uniquely identified. Entities are used to represent the main objects of interest in a database, such as customers, employees, or products. They are depicted as rectangles in an ER diagram and are connected through relationships to other entities. The entity is the fundamental building block of the ER model and is used to define the structure and organization of a database.

Weak entity types are entity types that cannot exist independently and depend on another entity for their existence. They have a partial or total dependency on the identifying entity, known as the owner entity. Weak entities are identified by their relationship with the owner entity, and they typically have a weak key that includes the owner entity's primary key as part of their own primary key. Without the owner entity, a weak entity cannot be uniquely identified or exist on its own. Therefore, the correct answer is "Weak."

The correct answer is subclass/superclass & specialization/generalization. The EER model extends the ER model by including the concepts of subclass/superclass and specialization/generalization. Subclass/superclass allows for the creation of specialized entities that inherit properties from a more general entity. Specialization/generalization allows for the creation of new entities by specializing or generalizing existing entities. These concepts enhance the modeling capabilities of the EER model and provide more flexibility in representing complex relationships and hierarchies in a database system.

An entity type refers to a collection of entities that share the same attributes. In an entity-relationship (ER) diagram, an entity type represents a category or class of objects that have similar characteristics. It serves as a template or blueprint for creating individual entities within that category. An entity type helps in organizing and structuring data by grouping related entities together based on their common attributes.

The participation constraint refers to the minimum number of relationships that are required for an entity to participate in. It specifies the minimum number of occurrences of one entity that must be associated with occurrences of another entity in a relationship. Therefore, the correct answer is "min # of relationships required."

The key attribute is chosen after carefully studying the user requirements. This implies that the selection of the key attribute is based on the specific needs and preferences of the users. By analyzing the user requirements, one can identify the essential attributes that are crucial for the functioning and effectiveness of the system. Therefore, the user requirements serve as a guide in determining the key attribute for the system.