Modeling Data in the Organization
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1. E-R Model Notation 2. Modeling the Rules of the Organization 3. Modeling Entities and Attributes 4. Modeling Relationship
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Modeling Data in the Organization
- 1. IS-DBS 213 Presented By: Dr. Rosemarie S. Guirre The Use of DBMS and the Database
- 2. WRAP UP The Database Environment and Development Process Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Data Information Data vs. Information Database Metadata DBMS Data Dictionary Data Models Types of Models Relational Model Keys ERD Data Mining Components of DB DB Dev. Process
- 3. Modeling Data in the Organization IS-DBS 313-2 1. E-R Model Notation 2. Modeling the Rules of the Organization 3. Modeling Entities and Attributes 4. Modeling Relationship TOPICS Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2
- 4. Entity-Relationship Model Models conceptual database design in terms of entities, attributes, and relationships between entities E-R Model Developed by Chen in 1976 Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Enhanced E-R model (EER model)
- 5. Entity-Relationship Symbols Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Attribute Relationship Entity
- 6. ER SYMBOLS Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entity Symbols STRONG ENTITY ASSOCIATIVE ENTITY
- 7. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entity Symbols ASSOCIATIVE ENTITY
- 8. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entity Symbols STRONG ENTITY
- 9. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entity Symbols
- 10. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 ER SYMBOLS Attribute Symbols ATTRIBUTE {MULTIVALUED} ATTRIBUTE [DERIVED] ATTRIBUTE
- 11. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Attribute Symbols STRONG ENTITY
- 12. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Attribute Symbols ATTRIBUTE
- 13. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Attribute Symbols {MULTIVALUED} ATTRIBUTE
- 14. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Attribute Symbols [DERIVED] ATTRIBUTE
- 15. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 ER SYMBOLS Relationship Symbols RELATIONSHIP IDENTIFYING RELATIONSHIP
- 16. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Types of Relationship Symbols
- 17. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Identify ER Symbols Attribute Relationship Entity
- 18. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 ER SYMBOLS MANDATORY ONE MANDATORY MANY OPTIONAL ONE OPTIONAL MANY MANY TO MANY
- 19. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 MANDATORY ONE
- 20. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 OPTIONAL MANY
- 21. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 MANY TO MANY
- 22. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 MANDATORY MANY
- 23. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 OPTIONAL ONE
- 24. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 ER SYMBOLS UNARY One entity BINARY 2 1 TERNARY 2 1 3 2 entities 3 entities
- 25. E-R Model Constructs person, place, object, event, concept (often corresponds to a row in a table) Entity (instance) collection of entities (often corresponds to a table) Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entity Set or Type Entities
- 26. Strong vs Weak Entities exist independently of other types of entities has its own unique identifier Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 represented with single-line rectangle STRONG ENTITY
- 27. Strong vs Weak Entities Does not have a unique identifier dependent on a strong entity…cannot exist on its own Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 represented with double-line rectangle
- 28. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 STRONG ENTITY WEAK ENTITY EMPLOYEE HAS emp_id emp_name date_of_birth dep_name mid_name first_name last_name
- 29. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Analyze the flow
- 30. Entity has attributes links together All relationships for the associative entity should be many Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Independent of the other entities ASSOCIATIVE ENTITY preferably has a unique identifier, and should also have other attributes participating in other relationships other than the entities of the associated relationship
- 31. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 ASSOCIATIVE ENTITY CERTIFICATE ASSOCIATIVE ENTITY EMPLOYEE COURSE emp_id emp_name cert_num date_completed course_id course_title
- 32. What Should an Entity Be? An object that will have many instances in the database SHOULD BE: An object that will be composed of multiple attributes Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 An object that are trying to model
- 33. An Entity Should Not Be? A user of the database system An output of the database system (e.g. a report) Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2
- 34. INAPPROPRIATE ENTITIES Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 System user System output Appropriate entities
- 35. E-R Model Constructs Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Entities THINGS TANGIBLE ROLES PLAYED ORGANIZA- TIONAL UNITS DEVICES INCIDENTS, EVENTS, INTERACTIONS SITES LOCATIONS Airplane Book Vehicle Document Worksheet Employees Customer Doctor Patient End User System Admin Division Department Section Task Force Work group Sensor Timer Controller Printer Keyboard Mouse Button Flight Service Call Logon Logoff Contract Purchase Payment
- 36. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 E-R Model Constructs property or characteristic of an entity or relationship type (often corresponds to a column in a table) Attributes
- 37. Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 E-R Model Constructs Primary Key - unique Types of Attributes Foreign Key – PK in another DB
- 38. Relationship Set or Type E-R Model Constructs link between entities (corresponds to primary key-foreign key equivalencies in related tables) Relationship (instance) category of relationship…link between entity types Presented By: Dr. Rosemarie S. Guirre | IS-DBS 213-2 Relationship
- 39. Prepared By: Dr. Rosemarie S. Guirre | IS-DBS 313-2 END OF MODULE 1
Editor's Notes
- Entity-Relationship Model a detailed, logical representation of the entities, associations, and data elements for an organization or business area. (E-R Model) Models conceptual database design in terms of entities, attributes, and relationships between entities Developed by Chen in 1976 Enhanced by others over the years Enhanced E-R model (EER model)
- Entity-Relationship Symbols Entity a “thing” in the real world has an independent existence Attribute(s) One specific piece of information about a thing a property of the entity has a value (or value set or domain)
- Relationship Naturally occurring association among specific things Occur in two directions Cardinality/multiplicity
- 1. RELATIONSHIP 2. IDENTIFYING RELATIONSHIP
- Cardinality the number of instances of an entity that are associated with another entity Specify number of entity types involved
- MANDATORY ONE
- OPTIONAL MANY
- MANY TO MANY
- MANDATORY MANY
- OPTIONAL ONE
- Degree of Relationship number of entities that participate in the relationship Unary (recursive) degree one A relationship between instances of one entity. One entity related to another of the same entity type Binary degree two A relationship between instances of two entities Entities of two different types related to each other Ternary A relationship between instances of three entities Entities of three different types related to each other
- Identifying relationship – links strong entities to weak entities – represented with double line diamond
- Associative Entities It’s an entity – it has attributes AND it’s a relationship – it links entities together When should a relationship with attributes instead be an associative entity? – All relationships for the associative entity should be many – The associative entity could have meaning independent of the other entities – The associative entity preferably has a unique identifier, and should also have other attributes – The associative may be participating in other relationships other than the entities of the associated relationship
- Associative entity involves a rectangle with a diamond inside. Note that many to many cardinality symbols face toward the associative entity and not toward the other entities
- An Entity is a thing the users need to know (i.e, record) something about.
- Identifier (primary key / key attribute) An attribute (or attributes) selected as the unique, identifying characteristic for an entity. Foreign Key An attribute (or attributes) in one database table that is the primary key in another database table
- Relationship Naturally occurring association among specific things Occur in two directions Cardinality/multiplicity