Introduction to Database

CIS458.101

Chapter 1

Sungchul Hong

Database System

• The most important development in the field of software engineering.

• Database serve as the foundation for considerable progress in the basic science fields ranging from computing to biology.

Introduction

• Database– A collection of related data.

• DBMS (Database Management System)– The software that manages and controls access

tot the database.

• Database application– A program that interacts with the database at

some point in its execution.

Examples of Databases

• Supermarket– Inventory– Customer service

• Credit card

• Booking a ticket at the travel agents

• Using the local library

• University

Traditional File-Based Systems

• Each program defines and manages its own data.

• Separation and isolation of data

• Duplication of data

• Data dependence

• Incompatibility of files

• Fixed queries of application program

Database Approach

• A shared collection of logically related data, and a description of this data, designed to meet the information needs of an organization.

• System catalog (data dictionary)

• Program-data independence.

File-Based System

Sales Files

Data entry & report

File handling routines

File definition

The Database Management System (DBMS)

• A software system that enables users to define, create, maintain, and control access to the database.

• Data Definition Language(DDL)• Data Manipulation Language (DML)

– Structured Query Language (SQL)

• Views– Level of security, customization, provide consistent

structure

Components of the DBMS Environment

• Hardware – Client-server architecture– Backend, front end

• Software– DBMS, application programs, SQL

• Data– Operational data, meta data

• Procedure– Instructions and rules

• People

Roles in the Database Environment

• Data Administrator (DA)– Responsible for the management of the data resource

including database planning, development and maintenance of standards, policies, and procedures, and conceptual/logical database design.

• Database Administrator (DBA)-more technical– Responsible for the physical realization of the database,

including physical database design and implementation, security and integrity of the application users.

Roles in the Database Environment (2)

• Database Designer– Logical database designer

• Identifying the data, relationship between the data, and the constraints on the data.

• Business rules.

– Physical database designer• Mapping the logical database design into a set of tables and

integrity constraints.

• Selecting specific storage structures

• Designing security measures required on the data

Roles in the Database Environment (3)

• Application Developer– Provide the required functionality for the end-

users.

• End-Users– Naïve users– Sophisticated users.

Data Redundancy

Advantages of DBMS

• Control of data redundancy• Data consistency• More information from the same amount of data• Sharing of data• Improved data integrity• Improved security• Enforcement of standards

Advantages of DBMS (2)

• Economy of scale• Balance of confliction requirements• Improved data accessibility and responsiveness• Increased productivity• Improved maintenance through data independence• Increased concurrency• Improved backup and recovery services

Disadvantages of DBMS

• Complexity

• Size

• Cost of DBMS

• Additional hardware costs

• Cost of conversion

• Performance

• Higher impact of a failure

History of DBMS

• Apollo moon-landing project (1960s)– GUAM (Generalized Update Access Method)– Hierarchical structure

• IMS (Information Management System) (mid 1960s)– Serial storage – device (Tape recorder)

• IDS (Integrated Data Store) (mid 1960s)– Network DBMS

• CODASYL (Conference on Data Systems Languages)

History of DBMS

• DBTG (Data Base Task Group) – 1967• Relational Model – E. F. Codd, 1970

– R– SQL– DB2, SQL/DS, Oracle

• INGRES II, Informix, Access, FoxPro, Paradox, Interbase, and R:Base

• ER model – Chen, 1979– Semantic data modeling

• Object-Oriented DBMS, Object-Relational DBMS