3902 Chapter 1

1
Ch 1

• Database applications
• Database
• Database Management System
• Characteristics
• Actors
• Advantages
• Implications
• When not to use a DBMS

2
Our focus

• Database applications
• traditional
• multimedia - pictures, video, sound
• scientific databases
• - GIS maps, weather, satellite images
• - biological database DNA sequence analysis
• warehouse, OLAP - analysis, decision making
• real-time, active databases - industrial
  processes
• deductive databases - combination of inference
  and databases

3

• Database
• collection of related data
• represents some aspect of the real world
• logically coherent collection
• built with a specific purpose in mind
• could be anywhere - notebook, spreadsheet,
  Access, Oracle, could be manual / could be
  computerized
• Data
• known and recordable facts - meaningful
• name, phone number, address, grade, ...

4

• Database Management System (DBMS)
• collection of software facilitating the
  definition, construction and manipulation of
  databases

DBMS
Meta data
Request manager
Storage manager
Applications / Queries
Stored database
Users/actors
5

• Database Management System (DBMS)
• Definition (design), construction, manipulation

• Definition
• record structure
• data elements
• names
• data types
• constraints
• etc

• Manipulation
• querying
• updating

• Construction
• create database
• files
• populate the
• database with
• records

6
Sample database - structure

• We must define each structure
• name / location
• attribute names
• attribute data types

Course
CName
CNo
CrHrs
Dept
Student
Name
StNo
Class
Major
Section
SId
CNo
Semester
Year
Instructor
GradeReport
StNo
Sid
Grade
PreCNo
CNo
Prerequisite
7
Sample database - rows
Course CName CNo CrHrs Dept
Database 3380 3 CS
C 2606 3 CS
Student Name StNo Class Major
Smith 17 1 CS
Brown 8 2 CS
GradeReport StNo Sid Grade
17 25 A
Section SId CNo Semester Year Instructor
17 43 B
32 8803 Spring 2000 Smith
25 8803 Winter 2000 Smith
43 2606 Spring 2000 Jones
8

• Characteristics of the Database approach
• single repository of data
• sharable by multiple users
• concurrency control
• transaction control
• OLTP
• self-describing - system catalogue contains meta
  data
• program-data independence
• some changes to the database are transparent to
  programs/users
• multiple views of data - to support individual
  needs of programs/users

9

• Database Actors
• Database Administrator (DBA) - authorizing
  access to the database - coordinating and
  monitoring its use - acquiring software and
  hardware as needed - solving problems such as
  breach of security or poor system performance
• Database Designers/Modelers - identifying the
  data to be stored - choosing appropriate data
  structure
• End-users - access to the database
  querying, updating, generating reports
• Software Engineers - developing application
  programs

10

• Advantages of the Database approach
• (capabilities we would look for in a DBMS)
• controlled redundancy
• persistent storage
• efficient execution of queries
• multiple user interfaces
• representation of complex relationships
• controlled/authorized access to data
• enforcing integrity constraints
• backup and recovery

11

• Implications of the Database approach
• standards enforcement
• DBA can enforce standard naming conventions, etc
• reduced application development time
• adding new functionality to an existing database
  is easy
• flexibility
• adding new data and making some types of changes
  is easy
• up-to-date information - due to sharable
  characteristic
• economies of scale - due to sharable resources
  the whole organization can make one investment

12

• When not to use a DBMS
• overhead costs are too great
• high initial investment
• generality
• overhead of security, concurrency control,
  recovery, integrity
• data and applications are simple, well-defined,
  not expected to change
• stringent real-time constraints
• multi-user environment not needed