Modern Systems Analysis and Design Chapter 7-9

Modern Systems Analysis and Design Chapter 7-9 Data Modeling Concepts 1. Conceptual Data Model: A high-level representation of organizational data structure, independent of any specific database system. 2. Entity-Relationship Data Model (E-R Model): A detailed logical model depicting entities, relationships, and data elements in an organization. 3. Entity-Relationship Diagram (E-R Diagram): A graphical representation of an E-R model. 4. Entity Type: A classification of entities that share common traits. 5. Entity Instance: A single occurrence of an entity type. 6. Attribute: A property or characteristic of an entity of interest to the organization. 7. Candidate Key: An attribute or combination of attributes that uniquely identifies an entity instance. 8. Identifier: A selected candidate key used as the unique identifier for an entity type. 9. Multivalued Attribute: An attribute that can have multiple values for a single entity instance. 10. Repeating Group: A collection of multiple related multivalued attributes. 11. Required Attribute: An attribute that must have a value for every entity instance. 12. Optional Attribute: An attribute that may not have a value for every entity instance. 13. Composite Attribute: An attribute made up of meaningful component parts. 14. Derived Attribute: An attribute whose value is calculated from other attributes. 15. Relationship: An association between instances of one or more entity types. 16. Degree: The number of entity types participating in a relationship. 17. Unary Relationship: A relationship occurring within a single entity type (recursive). 18. Binary Relationship: A relationship involving two entity types; the most common form. 19. Ternary Relationship: A simultaneous relationship among three entity types. 20. Cardinality: The number of permissible instances of one entity type associated with another. 21. Associative Entity: An entity that links multiple entity instances and includes relationship-specific attributes. --- Specialization and Business Rules 1. Subtype: A subgroup of an entity type, possessing distinct attributes or relationships. 2. Supertype: A general entity type that relates to one or more subtypes. 3. Total Specialization Rule: All supertype entities must belong to a subtype. 4. Partial Specialization Rule: Supertype entities may or may not belong to a subtype. 5. Disjoint Rule: An entity instance can belong to only one subtype at a time. 6. Overlap Rule: An entity instance can be part of multiple subtypes simultaneously. 7. Business Rules: Specifications maintaining the integrity of the data model. --- Object-Oriented Modeling Concepts 1. Object: An entity with defined roles, states, behaviors, and identity. 2. State: The properties and values of an object. 3. Behavior: The actions and reactions of an object. 4. Object Class: A logical grouping of objects with similar attributes and behaviors. 5. Class Diagram: A visual representation of the structure of an object-oriented model. 6. Operation: A function provided by class instances. 7. Encapsulation: Hiding an object’s internal details from the outside. 8. Constructor Operation: A method for creating new instances of a class. 9. Query Operation: An operation that retrieves object state without changing it. 10. Update Operation: Alters the state of an object. 11. Association: A relationship connecting object classes. 12. Multiplicity: Indicates how many objects participate in a relationship. 13. Abstract Class: A class with no direct instances. 14. Concrete Class: A class capable of having actual instances.