Transcript Basics of data management

The Context of Database
Management
Chapter 1, McFadden,
Hoffer & Prescott
Data and Information
DATA: Facts concerning people, objects, vents or
other entities. Databases store data.
INFORMATION: Data presented in a form
suitable for interpretation.
Data is converted into information by programs
and queries. Data may be stored in files or in
databases. Neither one stores information.
KNOWLEDGE: Insights into appropriate actions
based on interpreted data.
Knowledge Generation
DATA
INFORMATION
Basic Principles
DATABASE: A shared collection of interrelated
data designed to meet the varied information
needs of an organization.
DATABASE MANAGEMENT SYSTEM: A
collection of programs to create and maintain a
database.
Define
Construct
Manipulate
Files or Databases
Files
Databases
 program-data dependence
 duplication of data
 limited data sharing
 lengthy development time
 excessive program
maintenance
 a lot of experienced
programmers and
developers
 robust technology
 program-data
independence
 minimal data redundancy
 improved data consistency,
quality, accessibility, and
sharing
 increased productivity and
less maintenance
Database vs File Systems
Program 1
Meta-Data
Program 2
Meta-Data
Program 3
Meta-Data
Program 1
Program 2
Program 3
FILE SYSTEM
Data
DATABASE
MetaData
Data
Objectives of a DBMS
Approach
SELF-DESCRIBING
DATA INDEPENDENCE
MULTIPLE VIEWS
MULTIPLE USERS
Database Management
Systems
UTILITY
PROGRAMS
DATA
METADATA
ACCESS ENGINE
Example of Data
Course
Section
MIS 3353 100
MIS 3353 200
Semester Name
Rank
Su 01
Kemp
Instr
Su 01
Schwarzkopf Assoc P
MIS 3373 200
Su 01
Kemp
MIS 4663 900
Fa 01
Schwarzkopf Assoc P
MIS 4663 901
Fa 01
Van Horn
Instr
Prof
Example of Metadata
Data Item
Name
Type
Course
Char
Value
Length Min Max Description
7
Three digit department reference and 4
digit course number
Section
Integer 3
001 900 Section number
Semester Char
10
Semester and year
Name
Char
30
Instructor name
Rank
Char
10
Instructor rank
Database Access
USER
INTERFACE
DATABASE
PROGRAM
Evolution of data Structures
History of Database
Management
File Management Systems
Hierarchical Model
IBM “Information Management System (IMS)” 1966
Network Model
Charles Bachman’s “Integraded Data Store (IDS)” 1965
Conference on Data Systems Languages /DataBase Task
Group CODASYL/DBTG (1971)
Relational Model
E.F. Codd, 1970
File Management Systems
Provided facilities to extract data and
share files, but did not implement any
way to connect records in one file to
those in another. Relationships had to be
implemented in application code.
Hierarchy
SECTION
STUDENT
COLLEGE
INSTRUCTOR
COLLEGE
Each file can have only one parent. To implement a second
“parent” (COLLEGE) we have to implement a shadow copy.
Network
SECTION
STUDENT
INSTRUCTOR
COLLEGE
Each file can have several parents. Both SECTION and
COLLEGE are “parent” files..
Structured Databases
Relationships were implemented by
physical pointers (called “sets”) which
allowed records to be connected in
different files. Hierarchical databases
allow only one parent set; networks allow
several. These permit efficient processing
but the sets must be constructed on data
entry and cannot be rearranged later.
Relational
SECTION
SECTION-STUDENT
SECTION-INSTRUCTOR
SECTION-KEY
STUDENT-KEY
SECTION-KEY
INSTRUCTOR-KEY
STUDENT
INSTRUCTOR
COLLEGE-KEY
COLLEGE-KEY
COLLEGE
Each file can have several parents. Both SECTION and
COLLEGE are “parent” files..
Relational Models
Relational models implement relationships
with matched data values in related files
(called primary and foreign keys). Any
attributes can be matched. The
connection is established at retrieval so
interconnections can be developed as
needed.
Relational Terminology
Entity
Person, place, thing or event about which we
wish to keep data
Attribute
property of an entity
Relationship
an association among entities (entity
records)