DATABASE MANAGEMENT SYSTEMS

1
DATABASE MANAGEMENT SYSTEMS
2
OVERVIEW

• DATA HAS VALUE
• HIERARCHY OF DATA
• FIELD, RECORD, FILE, DATABASE
• FILE PROCESSING
• FILE ACCESS
• KEY FIELD
• SEQUENTIAL ACCESS
• DIRECT ACCESS
• PROBLEMS WITH FILE PROCESSING

3
OVERVIEW (contd)

• DATABASE MANAGEMENT
• DIFFERENCES BETWEEN FILE PROCESSING AND DATABASE
  MANAGEMENT
• COMPONENTS OF DBMS
• DATA DEFINITION LANGUAGE
• DATABASE INTERROGATION
• DATA MANIPULATION LANGUAGE
• DATA DICTIONARY
• DATA MODELS
• HIERARCHICAL
• NETWORK
• RELATIONAL
• OBJECT-ORIENTED STRUCTURE

4
DATA HAS VALUE

• DISCOVER CARD STORY
• NEWSPAPERS SELL INFORMATION

5
HIERARCHY OF DATA
BIT BYTE
FIELD
RECORD
FILE
DATABASE
NAME ADDRESS PHONE
6
FILE PROCESSING

• ONE FILE PER APPLICATION

7
FILE ACCESS

• KEY FIELD
• ACCESS
• SEQUENTIAL HAVE TO SORT FILE EACH TIME NEW
  RECORD IS ADDED
• DIRECT ACCESS MUST KNOW WHERE DATA IS LOCATED ON
  HARD DISK
• KEY TRANSFORMATION
• INDEX
• INDEXED SEQUENTIAL ACCESS METHOD
• ALLOWS BOTH DIRECT AND SEQUENTIAL ACCESS

8
KEY TRANSFORMATION
9
INDEX
10
INDEXED SEQUENTIAL ACCESS METHOD (ISAM)
11
DIFFERENCES BETWEEN FILE PROCESSING AND DATABASE
MANAGEMENT SYSTEMS
12
FILE PROCESSING(mostly 3rd gen lang)
CHECKING
CONTAINS NAME, ADDRESS, CHECKING TRANSACTIONS
PRG
DATA DUPLICATION
DATA
SAVINGS
CONTAINS NAME, ADDRESS SAVINGS TRANSACTIONS
PRG
DATA
13
DATA DUPLICATION

• DATA DUPLICATION LEADS TO
• USE OF EXCESS SECONDARY STORAGE
• POSSIBILITY OF LACK OF DATA INTEGRITY

14
DATA DEPENDENCE
SAMPLE PROGRAM FILE PROCESSING

• 10 READ (5, 100) NAME, ADDRESS
• 20 WRITE (6, 110) NAME, PAY
• 110 FORMAT (10X, 30X)
• 120 FORMAT (10X, F10.2)

DATA DEPENDENCE MEANS STRUCTURE OF DATA IS
EMBEDDED IN PROGRAM
15
LACK OF DATA INTEGRATION IN REPORTS
16
DATA BASE MANAGEMENT(4th gen lang)
DATABASE MGMT ALLOWS INTEGRATED REPORTS
SAVINGS
CHECKING
PRG
PRG
DATA BASE MANAGEMENT SYSTEM
NAME ADDRESS (NO DUPLICATION)
SAVINGS TRANS
CHECKING TRANS
17
DATA INDEPENDENCE
STRUCTURE OF DATA INCLUDES FIELD WIDTH, FIELD
TYPE
SAMPLE PROG DBMS

• CREATE FILE
• FIELD NAME
• FIELD WIDTH 10
• FIELD TYPE ALPHA
• FIELD ADDRS
• FIELD WIDTH 20
• FIELD TYPE ALPHA

.USE FILE READ NAME, ADDRESS WRITE NAME, PAY
18
COMPONENTS OF DBMS

• DATABASE MANAGEMENT SYSTEM SET OF COMPUTER
  PROGRAMS THAT
• DATABASE DEVELOPMENT
• DATA DEFINITION LANGUAGE
• DATABASE MAINTENANCE
• APPLICATION PROGRAMS, UTILITIES
• APPLICATION DEVELOPMENT
• DATA MANIPULATION LANGUAGE
• APPLICATION GENERATORS
• DATABASE INTERROGATION
• SQL, QBE

19
DATA DICTIONARY

• DATA DICTIONARY (DOCUMENTATION)

20
DATA DEFINITION LANG

• DATA DEFINITION LANGUAGE
• DATA CONTENTS (NAME,A DDRESS..)
• STRUCTURE (CHARACTER, FIELD WIDTH..)

21
COMPONENTS (contd)

• DATABASE INTERROGATION
• QUERY LANGUAGE (AD HOC)
• SQL (STANDARD QUERY LANGUAGE) SEE P. 239
• QBE (QUERY BY EXAMPLE) SEE P. 238
• REPORT GENERATO(REPORT FORMAT)
• DATABASE MAINTENANCE
• UPDATING, MODIFYING DATA IN DATABASES
• USE APPLICATION PROGRAMS UTILITIES

22
APPLICATION DEVELOPMENT

• DATA MANIPULATION LANGUAGE

23
DATA DICTIONARY

• DATA DICTIONARY
• DOCUMENTATION ON DATA (META-DATA)
• NEED NOT BE PART OF DBMS
• ACTIVE OR PASSIVE
• PAGE FOR EACH DATA ELEMENT

EMP_NAME DESCRIPTION FIELD TYPE FIELD
WIDTH FILES WHERE FOUND PROGRAMS WHERE FND OTHER
NAMES
24
DATABASE STRUCTURES

• HIERARCHICAL
• NETWORK
• RELATIONAL (TABLES)
• OBJECT ORIENTED
• DESIRED CHARACTERISTICS
• SPEED
• FLEXIBILITY

25
HIERARCHICAL
26
DEPT A
DEPT B
PROJECT 1
PROJECT 2
EMP 1
EMP 2
EMP 3
NETWORK
27
DEPT FILE
EMPLOYEE FILE
NAME
DEPNUM
TITLE
DEPNUM
DMGR
DLOC
RELATIONAL
28
ENTITY RELATIONSHIP DIAGRAMS
29
DATA NORMALIZATION
30
DATA METHOD PROCESSES
ENCAPSULATED
OBJECT-ORIENTED
(IGNORE)
31
LARGE DATA SETS

• DATA WAREHOUSE
• DATA MART
• DATA MINING

32
SUMMARY

• HANDLING DATA IS COMPLEX PROCESS
• ADVANCES IN METHODS OFTEN
• SOMETIMES METHODS DEPENDENT ON HARDWARE
  (SEQUENTIAL, DIRECT) OTHER TIMES NOT (DATABASE,
  OBJECT ORIENTED)