Download Principles of Information Systems

What is a Database?
SECTION 1
Database Technology and its
Evolution
• Decades long evolution
• Early data processing systems
• Today's systems
• New technology
File-Oriented Systems
• Early business computer systems
• Data processing systems
• Sequential processing
• Application program
Customer File
CustId
100
101
105
110
Sales-Representative File
CustName
Watabe Bros
Maltzl
Jefferson
Gomez
Address
Box 241, Tokyo
Salzburg
B 918, Chicago
Santiago
Country
Balance
Japan
Austria
USA
Chile
45,551
75,314
49,333
27,400
MonthTo
Date
Payments
40,113
65,200
49,811
28,414
Product File
ProdId
ProdDesc
ManufactureId
210
317
253
Cost
11.25
22.25
13.6
Manufacturer File
210
253
317
10
14
23
37
39
RepName
ManagerId
Rodney Jones
Masaji Matsu
Francois Moire
Elena Hermana
Goro Azuma
27
44
35
12
44
Office
Comm%
Chicago
Tokyo
Brussels
B.A.
Tokyo
10
11
9
13
10
Sales File
1035 Sweater
2241 Table Lamp
2518 Brass Sculpture
ManufacturerId
RepId
ManName
Kiwi Klothes
Brass Works
Llana Lamps
Address
Country
Auckland
Lagos
Lima
New Zealand
Nigeria
Peru
Price
22.00
33.25
21.20
Date
08-Feb
12-Feb
12-Feb
19-Feb
22-Feb
25-Feb
25-Feb
CustId
RepId
ProdId
Qty
100
101
101
100
101
105
110
14
23
23
39
23
10
37
2241
2518
1035
2518
1035
2241
2518
200
300
150
200
200
100
150
Data from a FileOriented System
Total
Price
6650.00
6360.00
3300.00
4240.00
4400.00
3325.00
3180.00
Random Access Processing
• Limitations of sequential processing
systems
• Sequential processing leads to additional
work
• Solved by :
Limitations of Traditional File
Systems
• Data redundancy
• Poor data control
• Inadequate data manipulation capabilities
• Excessive programming effort
Information as a Resource
• What is an Information System (IS)?
• A Management Information System (MIS)
• Data
• Information
• A database
• A database system
• Database Management System
Database Systems
• Data models
• Hierarchical model
• Pointer
Customer File
CustId
100
101
105
110
CustName
Watabe Bros
Maltzl
Jefferson
Gomez
Address
Box 241, Tokyo
Salzburg
B 918, Chicago
Santiago
Country
Japan
Austria
USA
Chile
Balance
45,551
75,314
49,333
27,400
MonthTo
Date
Payments
40,113
65,200
49,811
28,414
Invoice File
Inv.#
Date
1012 10-Feb
1015 14-Feb
1020 20-Feb
Invoice Line-Item File
CustId
100
110
100
RepId
Inv.#
39
37
14
Files with a Hierarchical
Relationship
1012
1012
1012
1015
1015
1020
1020
Line#
ProdId
Qty
1
2
3
1
2
1
2
1035
2241
2518
1035
2518
2241
2518
100
200
300
150
200
100
150
Total
Price
2200.00
6650.00
6360.00
3300.00
4240.00
3325.00
3180.00
CUSTOMER
INVOICE
INVOICE
LINE
CUSTOMER
INVOICE
STORE
INVOICE
LINE
CONTACT
• A network model
SALES REP
CUSTOMER
INVOICE
STORE
INVOICE
LINE
CONTACT
Relational Databases Systems
• Pointers - strengths and weaknesses
• E.F. Codd (1970)
An Illustration of Problems with Pointers
• For each customer, identify the manufacturer
of the ordered products.
No physical
connection
CUSTOMER
INVOICE
MANUFACTURER
INVOICE
LINE
PRODUCT
Codd’s proposal
• Tables
• Manipulation languages
Database Systems: Hardware,
Software, Data, and People
• A complete database systems consists of:
1 Hardware
2 Software
– DBMS
– Application software
DBMS
• Data dictionary
• Data security and integrity
Database
User View 3
User View 2
User View 1
Data Item
3 Data
4 People
Database & Instance
Typical components of a server
Memory
(RAM)
Disk
CPU
Database:
The actual database is a collection of tables or files that reside on the disk
Disk
Database
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
Memory
(RAM)
CPU
Two main types of database files:
Data
Metadata
Instance:
Software running in memory
Memory (RAM)
Disk
DBMS
Database
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
Instance
CPU
An Instance:
Multiple databases
Memory (RAM)
Disk
DBMS
DB01
Instance
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
DB02
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
CPU
Multiple Instances:
Single database
Memory (RAM)
Disk
DBMS
Instance 01
Database
Instance 02
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
CPU
Multiple Instances:
Single database
Memory (RAM)
DBMS
Disk
Instance 01
Database
Table 1
Table 4
Table 2
Table 5
Table 3
Table n
CPU01
Memory (RAM)
DBMS
Instance 02
CPU02
INSTANCE
OASIS
Multiple
databases