Entity Relationship Diagram Quiz

An attribute is indeed a property of an entity or a relationship type. In a database, entities represent real-world objects or concepts, and attributes describe the characteristics or properties of those entities. Similarly, relationship types define the associations between entities, and attributes can also be associated with these relationships. Therefore, it is correct to say that an attribute is a property of an entity or a relationship type.

Some attributes may be related to a particular entity. ex: the age of a member of staff is derivable from the age of birth.

The statement is true because an Entity-Relationship (ER) diagram is a visual representation of a database that focuses on the relationships between entities, rather than the technical aspects of the database design. It helps users understand and perceive the data by using simple and intuitive symbols to represent entities, attributes, and relationships. This abstraction of technical details allows users to focus on the conceptual understanding of the data rather than getting bogged down by the technical complexities of the database design.

An attribute is a property of an entity or a relationship type. In a database, entities represent real-world objects or concepts, and relationships represent the associations between these entities. Attributes describe the characteristics or properties of these entities or relationships. They can be used to store information such as names, ages, addresses, or any other relevant data. By defining attributes, we can define the structure and properties of the entities and relationships in a database, allowing us to organize and manage data effectively.

A strong entity type is an entity that does not depend on any other entity type for its existence. In other words, it can exist independently and has its own unique attributes. This is in contrast to a weak entity type, which relies on a strong entity type for its existence. Therefore, the correct answer is "an entity that is not existence-dependent on some other entity type."

A composite key is a candidate key with two or more attributes. In a database, a candidate key is a unique identifier for a record, and a composite key is formed by combining multiple attributes to create a unique identifier. This helps ensure that each record in a table is uniquely identified, even when individual attributes may not be unique on their own. Therefore, the given statement is true.

A candidate key is one or more attributes whose value uniquely identifies each entity.

ER (Entity-Relationship) aims to facilitate database design. ER is a conceptual data modeling technique that helps in designing the structure and organization of a database system. It allows the identification of entities, their attributes, and the relationships between them. By using ER diagrams, database designers can visually represent the entities and their relationships, which aids in understanding and designing the database schema. ER helps in creating a blueprint for the database, making it easier to translate the design into an actual database implementation.

A weak entity type is an instance that is existence dependent on some other entity type. This means that a weak entity cannot exist without a corresponding strong entity. It relies on the strong entity for its existence and cannot be uniquely identified without considering the strong entity it is associated with.

For example, the branch entity may have multiple values for the entity telephone

An attribute domain refers to a set of values that can be assigned to an attribute. This means that when defining an attribute for an entity or relationship type, the attribute domain determines the range of values that can be assigned to that attribute. It helps to maintain data integrity and consistency by restricting the possible values that can be stored in the attribute.

The majority of attributes are single-valued for a particular entity.

Entity types represent real-world objects or concepts that have a distinct existence in the database.

Relationship types describe how entities are related to one another.

Attributes are the properties or characteristics of an entity type.

File types and storage details are not fundamental concepts of the ER model; they are related more to the physical implementation of a database rather than its conceptual design.

The degree of a relationship refers to the number of participating entities in that relationship. It indicates how many entities are involved in the relationship. For example, if a relationship involves two entities, the degree of that relationship would be 2. The given answer correctly states that the degree of a relationship is determined by the number of participating entities.

The Entity-Relationship (ER) model, a conceptual modeling technique used in software engineering and database design, was indeed developed by Peter Chen in 1976, not 1980. This model provides a graphical representation of entities, their attributes, and the relationships between them. It serves as a foundation for understanding the structure of data within a system. Therefore, the statement claiming its development in 1980 is inaccurate; it was developed earlier, in 1976, by Peter Chen.

The address attribute of the branch entity can be subdivided into street city numbers.....

Each uniquely identifiable instance of an Entity is referred to simply as an entity. Other authors may refer to an entity as an entity occurence or entity instance.

A high-level conceptual model is independent of the particular DBMS and HW platform used to implement the database.

The correct definition of a simple attribute is: “An attribute that holds a single value for a single entity.” In the context of a database, a simple attribute is one that cannot be divided into subparts and holds only a single value for a particular entity. It’s the most basic form of attribute in an entity-relationship model.

The conceptual data model is a representation of the overall structure of a database, including its entities, attributes, and relationships. It provides a high-level view of the database and is independent of any specific database management system. The model describes not only the structure of the database but also the transactions that involve retrieving and updating data. Therefore, the correct answer is "describe the structure of a database and the associated retrieval and update transactions."

The Basic concept of the ER model is an Entity type, which represents a set of 'objects' in the 'real world' with the same properties. An Entity type has an independent existence and can be an object with a physical (or 'real existence') or an object with a conceptual (or 'abstract') existence

An entity type may have more than one candidate key. The choice of a primary key for an entity is based on considerations of attribute length the minimal number of attributes required.