1 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Session 5 Data Modeling ITE 252 Database Management

2 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Unary Relationships Bill of Materials problem. Basic parts make subassemblies; subassemblies make bigger subassemblies

3 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Ternary Relationships Involve three different entities Can be considered sets of binary relationships

4 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Ternary Relationships Intersection Data – date of the sale & number of units of the product sold Special five sided intersection data box - describes relationship b’twn two entities

5 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Many-to-Many Relationships Help minimize wasted space and optimize performance Intersection data: – Data that is part of many-to-many relationship and associated with specific, unique instance of related entities Associative entities: – Entity designed to associate key values from two entities in many-to-many relationship

6 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Many-to-Many Relationships

7 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Associative Entities The unique identifier of an associative entity is the combination of the unique identifiers of the two entities in the many-to-many relationships. e.g., a combination of Salesperson Number & Product Number Attributes

8 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Creating Data Models To create data model: – Identify entities – Identify attributes for each entity – Identify associations between entities Modeling tools include: – Manual (pencil and paper) {we will use this} – Generic draw program (e.g. Visio) – Custom modeling program (ERWIN)

9 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Visio Database Diagrams

10 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Example: General Hardware Company Wholesaler and distributor of various manufacturers’ tools and other hardware products Customers: – Hardware and home improvement stores, which in turn sell products at retail to individual consumers Acts as middleman: – Buys goods from manufacturers and sells to retail stores

11 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Example: General Hardware Company

12 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Example: General Hardware Company Dependent Entity diagonal hash mark in each corner Quantity is Intersection Data Entity keep track of how many units of each product each salesperson has sold

13 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Example: Good Reading Bookstores Chain of bookstores Needs to track data for: – Books – Publishers – Authors – Customers

14 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Example: Good Reading Bookstores Date, Price, and Quantity are Intersection Data in the many-to-many relationship between the BOOK and CUSTOMER entities.

15 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Database design process: Conceptual, logical, and design Main types of databases: Transactional, decision support (DSS), and hybrid Goal of data modeling: Create a well-structured database model that is simple, easy to read and comprehend, and scalable Basic database objects: Tables and indices Tables: Describe entities; are composed of columns (fields) and rows (records), with primary keys used as unique identifiers of records Summary

16 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Key components of relational database model: Entities and relationships Relationships may be binary, unary, or ternary, and have different cardinalities and modalities Many-to-many relationships support intersection data and associative entities In creating a data model, you (1) identify entities, (2) identify their attributes, and then (3) identify associations between entities Summary

17 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Key Terms Associative entity Balanced tree index Base object Binary relationship Binary tree index B-tree index Bulk loading Business rules Cardinality Clustered index Conceptual design Concurrency Database object Data diagram Data mart Data model Data warehouse Decision support system (DSS)

18 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Key Terms Entity-Relationship diagram (ERD) Entity-Relationship (E-R) modeling Field Hybrid database Identifier Index Intersection data Large object (LOB) data Leaf node Logical design Many-to-many (M-M) binary relationship Modality Node Nonclustered index Object-relation model (ORM) One-to-many (1-M) binary relationship

19 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management Key Terms One-to-one (1-1) binary relationship Online transaction processing (OLTP) Physical design Primary index Primary key Record Referenced entity Referencing entity Referential integrity Reporting database Scalable Secondary index Stakeholder Ternary relationship Transactional database Throughput Unary relationship

20 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Important Links The Entity Relationship Model – Wikipedia decriptino The Entity Relationship Model At Wal-Mart, World's Largest Retail Data Warehouse Gets Even Larger - This is a big, big, big data warehouse! At Wal-Mart, World's Largest Retail Data Warehouse Gets Even Larger Database Modeling Tools – nice listing of tools, some are free! Database Modeling Tools

21 Nassau Community CollegeProf. Vincent Costa Acknowledgements: Introduction to Database Management, All Rights ReservedIntroduction to Database Management international, open membership, not- for-profit technology standards consortium. Homework Read Chapter Three, pp HW#1: Create an E-R diagram modeled after the Good Reading Bookstores E-R diagram (Figure in your text and slide 14 here) for a publisher of music (limit to MP3s). Draw the diagram by hand and write up a description similar to the one in section (pp.95-95) in your text. Due next class