Documentation:Attribute

An attribute refers to a property or characteristic associated with an entity, class, or object.

Entities and Attributes

In data modeling, an entity represents a real-world object, concept, or thing (e.g., a customer, product, employee, etc.). Attributes provide details about these entities. They describe specific aspects or features of the entity. For example:

• An Employee entity may have attributes such as Name, Employee ID, Salary, and Department.
• A Product entity may have attributes like Product Name, Price, and Category.

Types of Attributes

• Persisted Attributes: Represent basic data types (e.g., strings, numbers, dates) and are stored automatically in the database.
• Transient Attributes: Represent basic data types (e.g., strings, numbers, dates) and are only kept in memory. When a user session end, the information is lost.
• Derived Attributes: Calculated or derived from other attributes (e.g., age based on birthdate) using an OCL expression
• Derived Settable Attributes: As Derived Attribute above, but also has a EAL expression that can write data back to the source attributes of the derivation.

Role in Data Modelling

Attributes play a crucial role in creating a data model (such as in a Class diagram). They help define the structure of a database schema and guide the creation of database tables.

Attributes provide essential information about entities in a data model, allowing us to represent and organize data effectively.