Database Management Systems COMP 281 / ITEC 281 / MIS 281 Fall 2005 Instructor: Justin M. Wang

Course Logistics Instructor information Roster Materials Communications Grading policy Submission & return policy Academic integrity Assignment submission date Maximum grade( % of total possible points) 1 week late 90 % More than 1 week late 50 % Except on the week 14 Database Management Systems

Course Introduction Course schedules and six modules Course outcomes Student responsibilities and expectations Course web site demonstration Basic Database Concepts. The relationship of a database to the organizational structure is also discussed. Entity Relationship Diagrams. This is the diagramming technique you will use for the conceptual design of your database system. Physical Database Structure. This will be created using Structured Query Language (SQL) and Oracle. Logical and Physical Design of the Database Application. This topic includes normalization and denormalization. Data Warehousing. This topic includes data warehousing techniques and terminology. Application Development of the Database System. This topic will include the components required for using these applications such as the architecture and the data access tools. Database Management Systems

Activity: Group Development Teams should be approximately 3 to 4 students Exchange contact information and communication methods Teams will be used primarily to review other team members’ designs A member from each team sends me an email about your group information Database Management Systems

Module 1 Database Concepts

Chapter 1 Database Systems Module 1: Database Concepts

Preview Data vs. information Database, different types of databases Database design Databases evolving Database systems vs. file systems Database Management Systems

Data vs. Information Data: Information: Raw facts; building blocks of information Unprocessed information Information: Data processed to reveal meaning Accurate, relevant, and timely information is key to good decision making Database Management Systems

Database Database—shared, integrated computer structure that houses: End user data (raw facts) Metadata (data about data) Database Management Systems

Database Management System (DBMS) Collection of programs that manages database structure and controls access to data Possible to share data among multiple applications or users Makes data management more efficient and effective End users have better access to more and better-managed data Database Management Systems

DBMS Interfaces Database Management Systems

Types of Databases Single-user: only one user at a time Desktop: single-user database running on a personal computer Multi-user: multiple users concurrently Workgroup: a small group of users Enterprise: a large group of users Database Management Systems

Internet, Intranet, and Extranet Databases Web-enabled Examples reflect B2C, B2B Large number of potential users Database Management Systems

Location of Databases Centralized: Distributed: Supports data located at a single site Distributed: Supports data distributed across several sites Database Management Systems

Uses of Databases Transactional (OLTP): Data warehouse (OLAP): Supports a company’s day-to-day operations Data warehouse (OLAP): Stores data used to make tactical or strategic decisions Often used to store historical data Structure is quite different Database Management Systems

Database Design Defines the database’s expected use Different approach needed for different types of databases Avoid redundant data Poorly designed database generates errors  leads to bad decisions  can lead to failure of organization Database Management Systems

Manual File Systems Traditionally composed of collection of file folders kept in file cabinet Organized with folders (ideally logically related) Were adequate for small amounts of data with few reporting requirements Lacked scalability Database Management Systems

Computer File System Could be technically complex DP specialists created file structures, wrote software, and designed application programs Resulted in numerous “home-grown” systems being created Database Management Systems

Basic File Terminology Database Management Systems

A Simple File System Database Management Systems

Problems with File System Requires extensive programming in a third-generation language (3GL) Structural dependence Data dependence: logical and physical format Limited data sharing Data redundancy Database Management Systems

Database vs. File System Problems inherent in file systems make using a database system desirable File system Many separate and unrelated files Database Logically related data stored in a single logical data repository Database Management Systems

Contrasting Database and File Systems Database Management Systems

DBMS Functions Data dictionary management Data storage management Data transformation and presentation Security management Multi-user access control Backup and recovery management Data integrity management Database access languages and application programming interfaces Database Management Systems

Disadvantages of DB Approach Higher initial cost for specialized software (DBMS) Higher learning curve for new DBMS software Organizational conflict on data definitions, data formats and coding Database Management Systems

Evolution of database technologies Database Management Systems

Summary of Chapter 1 Information is derived from data To implement and manage a database, use a DBMS Database design defines its structure Databases were preceded by file systems Because file systems lack a DBMS, file management lacks scalability DBMS were developed to address file systems’ inherent weaknesses Database Management Systems

Module 1: Database Concepts Chapter 2 Data Model Module 1: Database Concepts

Preview Basic data-modeling building blocks Major data models, and their advantages and disadvantages Database Management Systems

Data Models Relatively simple representation of complex real-world data structures Communications tool among the designer, the applications programmer, and the end user Database Management Systems

Data Model Building Blocks Entity is anything about which data are to be collected and stored Attribute is a characteristic of an entity Relationship describes an association among (two or more) entities Database Management Systems

The Evolution of Data Models Hierarchical Network Relational Entity relationship Object oriented Database Management Systems

The Hierarchical Model GUAM (Generalized Update Access Method): many smaller parts would come together as components of still larger components Information Management System (IMS): world’s leading mainframe hierarchical database system in the 1970s and early 1980s Database Management Systems

A Hierarchical Structure Database Management Systems

The Network Model Created to Represent complex data relationships more effectively Improve database performance Impose a database standard defined by Database Task Group (DBTG) Database Management Systems

Network Model Components Schema - conceptual organization of entire database Subschema - database portion “seen” by the application programs Schema Data Definition Language (DDL) - schema components Subschema DDL - allows application programs to access database components DML - manipulates database contents Database Management Systems

A Network Data Model Database Management Systems

The Relational Model Developed by Codd (IBM) in 1970 Considered ingenious but impractical in 1970 Conceptually simple Today, microcomputers can run sophisticated relational database software Database Management Systems

The Relational Model—Basic Structure Relational Database Management System (RDBMS) Table (relations) Relational schema - Visual representation of relational database’s entities, attributes and relationships Database Management Systems

A Relational Schema Database Management Systems

The Entity Relationship Model Widely accepted and adapted graphical tool for data modeling Introduced by Chen in 1976 Graphical representation of entities and their relationships in a database structure Database Management Systems

The ER Model - Basic Structure Entity relationship diagram (ERD) Entity instance (or occurrence) is row in table Types of relationships Diamond connected to related entities through a relationship line Database Management Systems

Relationships: Basic Chen ERD Database Management Systems

Relationships: Crow’s Foot ERD Database Management Systems

The Object Oriented Model Semantic data model (SDM) developed by Hammer and McLeod in 1981 Modeled both data and their relationships in a single structure known as an object Basis of object oriented data model (OODM) OODM becomes the basis for the object oriented database management system (OODBMS) Database Management Systems

OODM - Basic Structure Object: abstraction of a real-world entity Attributes describe the properties of an object Objects that share similar characteristics are grouped in classes Inheritance is the ability of an object within the class hierarchy to inherit the attributes and methods of classes above it Database Management Systems

A Comparison of the OO Model and the ER Model Database Management Systems

Development of Data Models Database Management Systems

Summary of Chapter 2 A data model is a (relatively) simple abstraction of a complex real-world data-gathering environment Basic data modeling components are: Entities Attributes Relationships Database Management Systems

Summary of Chapter 2 (cont’d) Hierarchical model - Based on a tree structure composed of a root segment, parent segments, and child segments Network model attempts to deal with many of the hierarchical model’s limitations Relational model - Current database implementation standard Object is basic modeling structure of object oriented model Database Management Systems

Wrap Up Assignment 1-1 Module 2 – Database design concepts Database Management Systems