How are attributes represented in an Entity Relationship Diagram?

Attributes in an Entity Relationship Diagram (ERD) are represented as ovals connected to their respective entities.

In an Entity Relationship Diagram, attributes are the properties or characteristics of an entity. They are represented as ovals and are connected to their respective entities by a line. Each attribute represents a piece of information that is relevant to the entity. For example, if the entity is a 'Student', the attributes could be 'Name', 'Age', 'Address', etc.

There are different types of attributes in an ERD. Simple attributes are those that cannot be divided further. For instance, 'Age' is a simple attribute of the 'Student' entity as it cannot be broken down into smaller components. On the other hand, composite attributes can be divided into smaller parts. For example, 'Address' can be broken down into 'Street', 'City', 'Postcode', etc.

Another type of attribute is a derived attribute. These are attributes whose values are calculated from other attributes. For example, 'Age' could be a derived attribute if the ERD has a 'Date of Birth' attribute. The 'Age' can be calculated from the current date and the 'Date of Birth'.

Multi-valued attributes are those that can have more than one value for a particular entity. For example, a 'Student' entity could have a 'Phone Number' attribute that can have multiple values if the student has more than one phone number.

In an ERD, these different types of attributes are represented differently. Simple and composite attributes are represented as ovals. Derived attributes are represented as dashed ovals. Multi-valued attributes are represented as double-lined ovals.

In summary, attributes in an ERD are represented as ovals and are connected to their respective entities. They provide more detailed information about the entities and can be of different types, each represented differently in the diagram.