DATABASE CONCEPTS

DATABASE MANAGEMENT

ACCESS DATA TO HELP WITH MANAGING

FROM SMALLEST TO LARGEST

CHARACTER: SINGLE SYMBOL

FIELD: GROUP OF CHARACTERS

ATTRIBUTES OR ENTITIES
RECORD: RELATED FIELDS

FILE: RELATED RECORDS

SEE EXAMPLE

DATABASE: COLLECTION OF LOGICALLY LINKED FILES

DATABASES USED IN A VARIETY OF PROGRAMS

EXAMPLE: CUSTOMER RECORDS IN BANKING

THREE BASIC ACTIVITIES

• UPDATING AND MAINTAINING COMMON DATABASES
• PROVIDING INFORMATION NEEDED FOR EACH END USER'S APPLICATION
• PROVIDING AN INQUIRY/RESPONSE AND REPORTING CAPABILITY

DATABASE DEVELOPMENT

NEED CONTROLED ACCESS TO CHANGES

NEED PROFESSIONAL ADMINISTRATOR

DATABASE INTERROGATION

USERS ASK QUESTIONS THROUGH QUERIES

RESPONSES ARE OBTAINED QUICKLY

2 LANGUAGES

1) SQL: STRUCTURED QUERY LANGUAGE

HOW QUERIES ARE MADE

BASIC FORM:

SELECT... FROM... WHERE

SELECT: LIST DATA FIELDS YOU WANT RETRIEVED

FROM: LIST THE FILES OR TABLES FROM WHICH WANT DATA TO BE RETRIEVED

WHERE: LIMITATIONS ON SEARCH

MAY USE HELP OPTIONS TO HELP MAKE QUERIES

2) QBE: QUERY BY EXAMPLE

USES POINT-AND-CLICK CAPABILITIES WHICH ARE EASIER FOR THE ENDUSERS

DATABASE MAINTENANCE

MUST BE CONTINUOUSLY UPDATED

APPLICATION DEVELOPMENT

MUCH EASIER TODAY

TEXT DATABASES

STORE DOCUMENTS ELECTRONICALLY

IMAGE AND MULTIMEDIA DATABASES

ARE TO STORE IMAGES ELECTRONICALLY. FOR EXAMPLE, ELECTRONIC ENCYCLOPEDIA

OPERATIONAL DATABASES
DISTRIBUTED DATABASES
EXTERNAL DATABASE
END USER DATABASES
DATA WAREHOUSES
DATA MART
    DATA MINING

• DATA ADMINISTRATION
• DATA PLANNING
• DATABASE ADMINISTRATION

HIERARCHICAL STRUCTURES

TREE FORM; EARLY FORMAT

NETWORK STRUCTURES

SHOWS COMPLEX RELATIONSHIPS

MANY TO MANY RELATIONSHIPS

RELATIONAL STRUCTURES

COMMON FORM TODAY

DATA VIEWED AS BEING IN THE FORM OF TABLES

OBJECT-OREINTED STRUCTURES

EASIER TO HANDLE MORE COMPLEX TYPES OF DATA (GRAPHS, PICTURES, VOICE)

MULTIDIMENSIONAL STRUCTURES

THREE OR MORE DIMENSIONS OF DATA. EASY WAY TO VISUALIZE DATA WITH MANY DIMENSIONS

EVALUATION OF STRUCTURES

RELATIONAL: EASY TO ASK QUESTIONS

PROCESSING SPEED LOWER THAN WITH HIERARCICAL OR NETWORK

KEY FIELDS

THE MOST IMPORTANT FIELD

UNIQUELY IDENTIFIES RECORD

ALSO HAVE POINTER FIELDS: POINT TO OTHER RECORDS

SEQUENTIAL ACCESS

FILES STORED IN A SPECIFIC FIELD BASED ON KEY FIELD

SLOW IF NEED IMMEDIATE UPDATING

DIRECT ACCESS

NOT SORTED IN ANY SPECIFIC SEQUENCE

HOW?

• KEY TRANSFORMATION
• MATHEMATICALLY TRANSFORM KEY FIELD
• INDEX
• INDEX OF RECORD KEYS AND ADDRESSES
• INDEXED SEQUENTIAL ACCESS METHOD (ISAM)
• SEQUENTIALLY STORED BASED ON KEY FIELD DATA

• DATA PLANNING
• REEQUIREMENTS SPECIFICATIONS
• CONCEPTUAL DESIGN
• LOGICAL DESIGN
• PHYSICAL DESIGN

This page was created by David Lewis on 6/18/97
This page last modified on 3/4/02