Concept of Database:
- Data, Information, and Knowledge
- Database is a set of records well organized using a particular logical data model
- Records: A records is an array of observed characteristics (or attributes) on one object (entity)
- Well Organized: 1) related records are connected; 2) no unnecessary redundancy
- Logical Data Models: Hierarchical, Network, Relational
- Database Development Process
- Data Modeling: Entity, Attribute, relationships
- Database Implementation: DBMS
Data Modeling (Bank Example: Customers, Accounts, and Transactions): Identify Objects, Attributes, and Relationships
- Identify Objects (entities): (1) objects can be tangible such as a customer or intangible such as an account or meeting; (2) objects must be observable at an instant in time; (3) objects must have multiple attributes (or dimensions) to be observed.
- Identify Attributes (characteristic data): (1) attributes must be relevant to the problem domain; (2) attributes cannot be foreign; and (3) attributes must be singled-valued, not composite or multi-valued.
- Identify Relationships: (1) A relationship reflects a verb action that link two objects; (2) A relationship allows one to navigate from one record to related records; and (3) if data on verb action needs to be recorded, then action records cuts in the middle between original two objects.
- Concepts: (maximum) mapping cardinally, optionality
Example 1: (Bank System) Customers own Accounts.
Example 2: An online store needs to have a database to track its customers, products, and orders so that customers can look for product description before order it and the store can find customer information to ship orders. Draw an Entity-Relationship Diagram for the store.
Reading Assignments: Chapter 2 of LIU
Writing Assignments:
- Correctness Questions: online at course.org
- Hands-on Question: A student club wants to have a database to manage its data on members, committees, and hosted events. The club assigns members to its numerous committees. It is possible that one member can serve in more than one committee and will chair at most one committee. Each year the club organizes many events. Each time, the club delegates one committee to be in charge of an event. Build an ERD to model the club’s business objects using Oracle Data Modeler.
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