Documentation:Attribute: Difference between revisions

Attribute

Latest revision as of 04:56, 17 May 2024

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 Modeling

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.

This page was edited more than 8 months ago on 05/17/2024. What links here

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-An '''attribute''' refers to a property or characteristic associated with an '''entity''', '''class''', or '''object'''. Let’s explore the concept of attributes:
+An '''attribute''' refers to a property or characteristic associated with an entity, class, or object.
-'''Entities and Attributes''':
+==== 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:
-In data modeling, an '''entity''' represents a real-world object, concept, or thing (e.g., a customer, product, employee, etc.).
+* 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.
-'''Attributes''' provide details about these entities. They describe specific aspects or features of the entity.
+==== 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.
+* '''[[Training:Derived attributes & associations|Derived Attributes]]''': Calculated or derived from other attributes (e.g., age based on birthdate) using an OCL expression
+* '''[[Documentation:Derived settable attributes|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.
-For example:
+==== Role in Data Modeling ====
+Attributes play a crucial role in creating a data model (such as in a [[Documentation:Class diagrams|Class diagram]]). They help define the structure of a database schema and guide the creation of database tables.
-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''':
-'''Simple Attributes''': Represent basic data types (e.g., strings, numbers, dates).
-'''Composite Attributes''': Composed of multiple simple attributes (e.g., an address attribute with sub-attributes like street, city, and postal code).
-'''Derived Attributes''': Calculated or derived from other attributes (e.g., age based on birthdate).
-'''Multivalued Attributes''': Can have multiple values (e.g., phone numbers for a contact).
-'''Key Attributes''': Part of the primary key that uniquely identifies an entity.
-'''Role in Data Modeling''':
-Attributes play a crucial role in creating a '''data model''' (such as an '''Entity-Relationship Diagram (ERD)''').
-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.