Chapter 1: The Database Environment and Development Process

1. Essentials of Database Management Jeffrey A. Hoffer, Heikki Topi, V. Ramesh Chapter 1:The Database Environment and Development Process Copyright © 2014 Pearson Education, Inc.

2. Basic DB Terms • Data: Meaningful facts, text, graphics, images, sound, video segments • A collection of individual responses from a marketing research • Information: Data processed to be useful in decision making • Pattern of geographical buying habit based on analysis of a marketing research • Metadata: Data that describes data

3. Data in Context Large volume of facts, difficult to interpret / make decisions

4. Information Useful for decision making / interpretation

5. Metadata Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and documentation (Data Dictionary)

6. Application #1 Application #2 Application #3 DBMS Database containing centralized shared data Database Systems

7. Database Systems • Collection of electronic data • Central repository of shared data • Stored in a standardized, convenient form. • Requires a Database Management System (DBMS)

8. File processing System Data Copyright © 2014 Pearson Education, Inc. Chapter 1 8

9. Advantages of Central Database • Reduce data redundancy • Same customer address for each Dept. • Reduce data inconsistency • New real time updates for every Dept. • Eliminate application-data dependency • Improve data sharing • Enforce standardization

10. Evolution of DB Models • File processing system (traditional) • Hierarchical • Network • Relational • Object-oriented • Object-relational

11. A schematic diagram of a hierarchical database (a) and a sample part of a hierarchical database showing relationships among different records (b) Hierarchical Database

12. A schematic diagram of a network database (a) and a sample of part of a network database showing relationships among different records (b) Network Database

13. Relational Database • A relational database is a collection of tables that are related to one another based on a common field. • A common field is called a primary key(s). • unique identifier in data model (ERD) • When the primary key of one table is represented in a second table to form a relationship, it is called a foreign key.

14. A schematic diagram of a relational database (a) and a sample part of a relational database showing different tables (b) Relational Database

15. Relating Tables Using a Common Field The primary key in the Employer table (EmployerID) is the common field that relates this table to the Position table. PositionID is the primary key in the Position table. The EmployerID field is a foreign key in this table. Primary keys can only have one occurrence in a table. Foreign keys may have multiple occurrences.

16. Relational Database • Advantages • Easier database design, implementation, management, and use • Ad hoc query capability with SQL • Powerful database management system

17. Figure 1-10a Evolution of database technologies

19. Database Applications • Personal Database – standalone desktop database • Workgroup Database – local area network (<25 users) • Department Database – local area network (25-100 users) • Enterprise Database – wide-area network (hundreds or thousands of users)

20. An Enterprise Data Warehouse Collection of historic… NOT current data…

21. Data Mining • Help to find hidden patterns and relationships in large databases to predict future behavior • “If a house is purchased, then new refrigerator will be purchased within two weeks 65% of the time.”

22. Components of the DB Environment • CASE Tools – computer-aided software engineering • Repository (data dictionary) – centralized storehouse of metadata • Database Management System (DBMS) – software for managing the database • Database – storehouse of the data • Application Programs – software using the data • User Interface – text and graphical displays to users • Database Administrators (DBA) – personnel responsible for maintaining the database • System Developers – personnel responsible for designing databases and software • End Users – people who use the applications and databases

23. Components of the DB Environment

24. Database Development Process Feasibility Study of Project Purpose – preliminary understanding Deliverable –request for project Requirement Analysis Conceptual Design Logical Design - Is the project worth looking at ? - Is the DB system worth building? Physical Design Implementation Maintenance

25. Database Development Process Purpose – state business situation and possible solution Deliverable –decomposed requirements Feasibility Study of Project Requirement Analysis Conceptual Design Logical Design • What do users need and want from the new system? • What the new system must do Physical Design Implementation Maintenance

26. Database Development Process Purpose–thorough analysis Deliverable – conceptual data model Feasibility Study of Project Requirement Analysis Conceptual Design Logical Design conceptual data model • next slide • example model from the web page Physical Design Implementation Maintenance

27. Conceptual Data Model

28. Database Development Process Feasibility Study of Project Purpose –information requirements structure Deliverable – logical database design Requirement Analysis Conceptual Design • Hierarchical DB • Network DB • Relational DB • Object Oriented Logical Design Physical Design Implementation Maintenance

29. Database Development Process Purpose –develop technology specs Deliverable – program/data structures, DB technology purchases… Feasibility Study of Project Requirement Analysis Conceptual Design Logical Design Physical Design • Define physical organization of data Implementation Maintenance

30. Database Development Process Purpose – testing, training, debugging, installation, documenting Deliverable – operational programs, documentation, training materials Feasibility Study of Project Requirement Analysis Conceptual Design Logical Design Physical Design Implementation Maintenance

31. Database Development Process Feasibility Study of Project Purpose –monitor, repair, enhance Deliverable – periodic audits Requirement Analysis Conceptual Design Logical Design Physical Design Implementation Maintenance

32. DB Development Schedule Gantt Chart shows time estimates of tasks

33. DB Development Schedule … PERT Chart shows dependencies between tasks

34. Incremental Commitment in DB Development • Project is reviewed at the end of each development phase • Re-justify the process under the light of new requirements and available resources • Renew commitment of stakeholders • Continue / Revise Scope / Cancel

35. Database Schema • is the definition that describes the entire configuration of the database, including all of its tables, relations, index, etc. • External Schema (User Views, Combination of Enterprise data model (top-down) and Detailed user views (bottom-up) • Conceptual Schema (E-R models) • Internal Schema • Logical structures • Physical structures

36. Figure 1-9 Three-schema architecture Different people have different views of the database…these are the external schema The internal schema is the underlying design and implementation Copyright © 2014 Pearson Education, Inc. Chapter 1 36