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Computational Course – Section 2

Internet, Data Representation & Database Management System

Unit 4: The Internet | Unit 5: Data Representation | Unit 6: Database Management System

Contents

Unit 4 – The Internet 4.1 Definition and Development 4.2 Internet Services 4.3 Uses of Internet 4.4 Internet Address 4.5 Important TU Questions Unit 5 – Data Representation 5.1 Number Systems 5.2 Decimal to Binary 5.3 Binary to Decimal 5.4 Decimal and Octal 5.5 Decimal and Hexadecimal 5.6 Binary and Octal 5.7 Binary and Hexadecimal 5.8 Octal and Hexadecimal 5.9 Fractional Conversions 5.10 Binary Addition 5.11 Binary Subtraction 5.12 Calculation Tips and Common Mistakes 5.13 Logic Gates 5.14 Logic Gate Problems 5.15 Boolean Laws and De Morgan's Theorems 5.16 Large Numerical Practice Bank Unit 6 – Database Management System 6.1 Database 6.2 DBMS 6.3 Database Approach 6.4 Database Models 6.5 Data Warehouse, Data Mart and Data Mining 6.6 Computational Nanoscience, Space Data and Computational Biology 6.7 Important TU Questions Final Section 2 Revision

UNIT 4 – THE INTERNET

4.1 Definition of Internet

The Internet is a worldwide interconnected network of computer networks that allows computers, mobile devices, servers and other digital devices to communicate and exchange information using standardized communication protocols.

It is often described as a network of networks because millions of private, public, academic, commercial and governmental networks are interconnected through communication technologies and protocols.

Exam definition: The Internet is a global system of interconnected computer networks that communicates using the TCP/IP protocol suite and provides various services such as electronic mail, file transfer and the World Wide Web.

Internet and World Wide Web are not the same

The Internet is the underlying global network infrastructure, whereas the World Wide Web (WWW) is one service that operates over the Internet. Other Internet services include e-mail, FTP and remote login.

Internet World Wide Web
Global network infrastructure. Information system operating over the Internet.
Supports many services. Mainly provides interconnected web pages and resources.
Uses several protocols. Primarily uses HTTP/HTTPS for web communication.

4.2 Important Internet Terms

4.3 Internet Services

1. Electronic Mail – E-mail

Electronic mail is a service used to send and receive digital messages through computer networks and the Internet.

An e-mail can contain:

Basic components of an e-mail address

username@domain

Example:

student@example.com

The part before @ generally identifies the mailbox/user, while the part after @ identifies the mail domain.

Common e-mail functions

2. File Transfer Protocol – FTP

FTP stands for File Transfer Protocol. It is a protocol designed for transferring files between computers over a network.

FTP can be used for uploading files from a client to a server and downloading files from a server to a client.

FTP operation Meaning
Upload Transfer file from local computer to remote server.
Download Transfer file from remote server to local computer.

3. Telnet

Telnet is a network protocol that allows a user to establish a remote terminal session with another computer.

It historically provided command-line remote access to networked systems. Because traditional Telnet does not provide the same level of encryption as secure alternatives, secure remote-access protocols are generally preferred for sensitive communication.

4. Usenet News

Usenet is a distributed discussion system in which users can participate in topic-based discussion groups known as newsgroups.

It was one of the earlier systems used for distributed online discussion and information sharing.

5. World Wide Web – WWW

The World Wide Web is a collection of interconnected digital resources that can be accessed through the Internet using web browsers.

Web pages are commonly linked through hyperlinks. Modern websites may contain text, images, audio, video, animation and interactive applications.

Basic web communication

User → Browser → Internet → Web Server → Web Resource → Browser

HTTP and HTTPS are commonly used for transferring web resources between browsers and web servers.

4.4 Uses of Internet

  1. Education and online learning
  2. Electronic mail
  3. Research and information retrieval
  4. Online banking
  5. E-commerce
  6. Digital communication
  7. Telemedicine
  8. Online government services
  9. Cloud computing
  10. File sharing
  11. Entertainment
  12. Social communication
  13. Remote work
  14. Scientific collaboration
  15. Online conferences and meetings

4.5 Internet Address

An Internet address is used to identify a device, service or resource on a network. Different forms of addressing are used for different purposes.

IP Address

An IP address is a numerical address used in Internet Protocol communication. The two major forms are IPv4 and IPv6.

IPv4

IPv4 uses a 32-bit address represented commonly as four decimal octets separated by dots.

Example: 192.168.1.10

IPv6

IPv6 uses a 128-bit address and was developed partly to provide a much larger address space than IPv4.

Domain Name

A domain name is a human-readable name used to identify an Internet resource.

www.example.com

URL

A Uniform Resource Locator (URL) specifies the location and access method for a resource.

https://www.example.com/folder/page.html

Major components may include:

Internet Address – Exam Comparison

Term Main purpose Example
IP address Numerical network addressing 192.168.1.10
Domain name Human-readable Internet name example.com
URL Identifies/location of a resource https://example.com/page

4.6 Important TU-Style Questions

10-Mark Questions

  1. Define Internet and discuss its major services.
  2. Explain the major Internet services with suitable examples.
  3. What is Internet? Explain e-mail, FTP, Telnet, Usenet News and WWW.
  4. Explain Internet addressing and distinguish IP address, domain name and URL.

5-Mark Questions

  1. What is FTP? Explain its uses.
  2. Explain World Wide Web.
  3. Write a short note on Telnet.
  4. Explain e-mail and its major components.
  5. What is URL? Explain its components.

2-Mark Questions

  • Define Internet.
  • What is WWW?
  • Define FTP.
  • What is an IP address?
  • What is a domain name?
  • What is URL?
  • What is Telnet?

UNIT 5 – DATA REPRESENTATION

Data representation is one of the most important computational topics because computers internally represent and process information using binary digits. A strong understanding of number systems, conversions, binary arithmetic and logic gates is therefore essential.

Exam priority: Unit 5 contains calculation-based questions. Students should practice the method, not merely memorize final answers. Always show intermediate calculations in numerical questions.

5.1 Number Systems

A number system is a systematic method of representing numbers using a defined set of digits and a base or radix.

Number system Base Digits used
Decimal 10 0–9
Binary 2 0, 1
Octal 8 0–7
Hexadecimal 16 0–9, A–F

In hexadecimal:

A=10, B=11, C=12, D=13, E=14, F=15

Positional Notation

In a positional number system, the value of a digit depends on both the digit and its position.

(dn...d2d1d0)b = Σ dibi

For fractional positions, powers become negative:

... + d-1b-1 + d-2b-2 + ...

Place Values

System Place values from right
Binary 20, 21, 22, 23...
Octal 80, 81, 82, 83...
Decimal 100, 101, 102, 103...
Hexadecimal 160, 161, 162, 163...

5.2 Decimal to Binary Conversion

For a whole decimal number, repeatedly divide by 2 and record the remainders. Read the remainders from bottom to top.

Example 1: Convert (45)10 into binary.
45 ÷ 2 = 22 remainder 1
22 ÷ 2 = 11 remainder 0
11 ÷ 2 = 5 remainder 1
5 ÷ 2 = 2 remainder 1
2 ÷ 2 = 1 remainder 0
1 ÷ 2 = 0 remainder 1

Reading remainders from bottom to top:

(45)10 = (101101)2
Example 2: Convert (100)10 into binary.
100 ÷ 2 = 50 R0
50 ÷ 2 = 25 R0
25 ÷ 2 = 12 R1
12 ÷ 2 = 6 R0
6 ÷ 2 = 3 R0
3 ÷ 2 = 1 R1
1 ÷ 2 = 0 R1
(100)10 = (1100100)2
Example 3: Convert (156)10 into binary.
156 ÷ 2 = 78 R0
78 ÷ 2 = 39 R0
39 ÷ 2 = 19 R1
19 ÷ 2 = 9 R1
9 ÷ 2 = 4 R1
4 ÷ 2 = 2 R0
2 ÷ 2 = 1 R0
1 ÷ 2 = 0 R1
(156)10 = (10011100)2

5.3 Binary to Decimal Conversion

Multiply each binary digit by its corresponding power of 2 and add the results.

Example 4: Convert (101101)2 into decimal.
1011012

= 1×25 + 0×24 + 1×23 + 1×22 + 0×21 + 1×20

= 32 + 0 + 8 + 4 + 0 + 1
= 45
(101101)2 = (45)10
Example 5: Convert (1101011)2 into decimal.
= 1×64 + 1×32 + 0×16 + 1×8 + 0×4 + 1×2 + 1×1
= 64 + 32 + 8 + 2 + 1
= 107
(1101011)2 = (107)10

5.4 Decimal and Octal Conversion

Decimal → Octal

Example 6: Convert (125)10 to octal.
125 ÷ 8 = 15 R5
15 ÷ 8 = 1 R7
1 ÷ 8 = 0 R1
(125)10 = (175)8
Example 7: Convert (500)10 to octal.
500 ÷ 8 = 62 R4
62 ÷ 8 = 7 R6
7 ÷ 8 = 0 R7
(500)10 = (764)8

Octal → Decimal

Example 8: Convert (735)8 to decimal.
= 7×82 + 3×81 + 5×80
= 7×64 + 3×8 + 5
= 448 + 24 + 5
= 477
(735)8 = (477)10

5.5 Decimal and Hexadecimal Conversion

Decimal → Hexadecimal

Example 9: Convert (254)10 to hexadecimal.
254 ÷ 16 = 15 R14
15 ÷ 16 = 0 R15

14 = E
15 = F
(254)10 = (FE)16
Example 10: Convert (1000)10 to hexadecimal.
1000 ÷ 16 = 62 R8
62 ÷ 16 = 3 R14
3 ÷ 16 = 0 R3

14 = E
(1000)10 = (3E8)16

Hexadecimal → Decimal

Example 11: Convert (2AF)16 to decimal.
A = 10
F = 15

= 2×162 + 10×161 + 15×160
= 2×256 + 10×16 + 15
= 512 + 160 + 15
= 687
(2AF)16 = (687)10

5.6 Binary and Octal Conversion

Binary and octal conversion is particularly fast because:

1 octal digit = 3 binary bits

Binary → Octal

Example 12: Convert (110101101)2 to octal.
Group binary digits from the right in groups of three:

110 | 101 | 101

110 = 6
101 = 5
101 = 5
(110101101)2 = (655)8

Octal → Binary

Example 13: Convert (572)8 to binary.
5 = 101
7 = 111
2 = 010
(572)8 = (101111010)2

5.7 Binary and Hexadecimal Conversion

Binary and hexadecimal conversion is also direct because:

1 hexadecimal digit = 4 binary bits

Binary → Hexadecimal

Example 14: Convert (101111001010)2 to hexadecimal.
Group from the right:

1011 | 1100 | 1010

1011 = B
1100 = C
1010 = A
(101111001010)2 = (BCA)16

Hexadecimal → Binary

Example 15: Convert (3F7)16 to binary.
3 = 0011
F = 1111
7 = 0111
(3F7)16 = (001111110111)2

5.8 Octal and Hexadecimal Conversion

There is no equally direct digit-for-digit relationship between octal and hexadecimal. The easiest examination method is to use binary as the intermediate system.

Example 16: Convert (725)8 to hexadecimal.
First convert octal to binary:

7 = 111
2 = 010
5 = 101

Therefore:
7258 = 1110101012

Group into four bits from the right:
0001 | 1101 | 0101

0001 = 1
1101 = D
0101 = 5
(725)8 = (1D5)16
Example 17: Convert (3A)16 to octal.
Hexadecimal to binary:

3 = 0011
A = 1010

3A16 = 001110102

Group into three bits:
00 | 111 | 010

Pad from left:
000 | 111 | 010

000 = 0
111 = 7
010 = 2
(3A)16 = (72)8

5.9 Fractional Number Conversion

Fractional conversion requires a different method from whole-number conversion. For a decimal fraction being converted into another base, repeatedly multiply the fractional part by the target base.

Decimal Fraction → Binary

Example 18: Convert (0.625)10 to binary.
0.625 × 2 = 1.250 → integer part 1
0.250 × 2 = 0.500 → integer part 0
0.500 × 2 = 1.000 → integer part 1
(0.625)10 = (0.101)2
Example 19: Convert (0.375)10 to binary.
0.375 × 2 = 0.750 → 0
0.750 × 2 = 1.500 → 1
0.500 × 2 = 1.000 → 1
(0.375)10 = (0.011)2

Binary Fraction → Decimal

Example 20: Convert (0.1011)2 to decimal.
= 1×2-1 + 0×2-2 + 1×2-3 + 1×2-4

= 1/2 + 0 + 1/8 + 1/16
= 0.5 + 0.125 + 0.0625
= 0.6875
(0.1011)2 = (0.6875)10

Decimal Fraction → Octal

Example 21: Convert (0.625)10 to octal.
0.625 × 8 = 5.000
(0.625)10 = (0.5)8

Decimal Fraction → Hexadecimal

Example 22: Convert (0.625)10 to hexadecimal.
0.625 × 16 = 10.000
10 = A
(0.625)10 = (0.A)16

Mixed Decimal Number → Binary

Example 23: Convert (25.625)10 to binary.
Integer part:
25 ÷ 2 = 12 R1
12 ÷ 2 = 6 R0
6 ÷ 2 = 3 R0
3 ÷ 2 = 1 R1
1 ÷ 2 = 0 R1

Therefore integer part = 11001.

Fractional part:
0.625 × 2 = 1.25 → 1
0.25 × 2 = 0.5 → 0
0.5 × 2 = 1.0 → 1
(25.625)10 = (11001.101)2

Mixed Binary Number → Decimal

Example 24: Convert (101.101)2 to decimal.
Integer part:
1×22 + 0×21 + 1×20 = 4 + 0 + 1 = 5

Fraction:
1×2-1 + 0×2-2 + 1×2-3
= 0.5 + 0 + 0.125 = 0.625
(101.101)2 = (5.625)10

Repeating/Approximate Fraction

Some decimal fractions do not terminate exactly in a particular base. In such cases the multiplication process continues until the required number of digits has been obtained or a repeating pattern becomes evident.

Example 25: Convert 0.1 decimal to binary approximately.
0.1×2 = 0.2 → 0
0.2×2 = 0.4 → 0
0.4×2 = 0.8 → 0
0.8×2 = 1.6 → 1
0.6×2 = 1.2 → 1
0.2×2 = 0.4 → 0

The pattern continues rather than terminating immediately.
(0.1)10 ≈ (0.000110011...)2

5.10 Binary Addition

Binary addition follows the same general principle as decimal addition, but only two digits, 0 and 1, are used.

A B Sum Carry
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1

The most important rule is:

1 + 1 = 102
Example 26: Add 1011 and 1101.
   1011
 + 1101
 -------
  11000
Rightmost column: 1+1 = 10 → write 0, carry 1.
Next: 1+0+1 = 10 → write 0, carry 1.
Next: 0+1+1 = 10 → write 0, carry 1.
Next: 1+1+1 = 11 → write 1, carry 1.
Final carry = 1.
10112 + 11012 = 110002
Example 27: Add 11101 and 10111.
   11101
 + 10111
 --------
  110100
111012 + 101112 = 1101002

5.11 Binary Subtraction

A B Difference Borrow
0 0 0 0
1 0 1 0
1 1 0 0
0 1 1 1

The important borrowing rule is:

102 − 12 = 12
Example 28: Subtract 1011 from 11001.
   11001
 - 01011
 --------
   01110
110012 − 10112 = 11102
Example 29: Subtract 001101 from 100000.
   100000
 - 001101
 --------
   010011
1000002 − 0011012 = 100112

Binary Subtraction with Multiple Borrowing

Example 30: Calculate 1000000 − 0001111.
   1000000
 - 0001111
 ---------
   0110001
10000002 − 11112 = 1100012

5.12 Calculation Tips and Common Mistakes

Calculation Tip 1 – Memorize powers of 2.
For fast binary-to-decimal conversion, remember:

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024...
Calculation Tip 2 – Remember the grouping rule.

Binary → Octal = group 3 bits.
Binary → Hexadecimal = group 4 bits.
Calculation Tip 3 – Do not reverse digits incorrectly.
In repeated division, write remainders from top to bottom but read them from bottom to top.
Calculation Tip 4 – Fraction method is opposite in appearance.
Whole number → repeated division.
Fraction → repeated multiplication.
Calculation Tip 5 – Check your answer.
After converting a number, convert the answer back to the original system when time permits. This is one of the safest ways to detect calculation mistakes.
Calculation Tip 6 – Hexadecimal values A–F.
Never forget: A=10, B=11, C=12, D=13, E=14, F=15.
Calculation Tip 7 – Valid digit check.
A number written in base b cannot contain a digit equal to or greater than b. For example, 128 is invalid in octal because octal digits stop at 7.
Calculation Tip 8 – Add leading zeros when grouping.
For binary → octal or hexadecimal, add zeros on the left if necessary. The numerical value does not change.
Calculation Tip 9 – Keep integer and fraction parts separate.
For a mixed decimal number such as 25.625, convert 25 and 0.625 separately and then join them.
Calculation Tip 10 – Binary addition.
When 1+1 occurs, write 0 and carry 1. When 1+1+1 occurs, write 1 and carry 1.
Calculation Tip 11 – Binary subtraction.
When subtracting 1 from 0, borrow from the next available 1. The borrowed value is represented as 10₂.
Common mistakes:
  • Reading repeated-division remainders in the wrong direction.
  • Using 8 or 9 as digits in octal.
  • Forgetting that A–F represent 10–15 in hexadecimal.
  • Grouping binary digits from the wrong side.
  • Using division instead of multiplication for fractional conversion.
  • Ignoring the fractional part of a mixed number.
  • Forgetting the carry during binary addition.
  • Forgetting the borrow during binary subtraction.
  • Writing a final answer without the base/subscript.

5.13 Logic Gates

A logic gate is an electronic circuit that performs a logical operation on one or more binary inputs and produces a binary output.

The basic logic gates are AND, OR and NOT. NAND, NOR, XOR and XNOR are also important gates used in digital systems.

AND Gate

The AND gate produces output 1 only when all inputs are 1.

Y = A · B
A B Y AND
ABY=A·B
000
010
100
111

OR Gate

The OR gate produces output 1 when at least one input is 1.

Y = A + B
A B Y OR
ABY=A+B
000
011
101
111

NOT Gate

The NOT gate has one input and produces the complement of that input.

Y = A'
A Y NOT
AY=A'
01
10

NAND Gate

NAND is the complement of AND.

Y = (A·B)'
A B Y NAND
ABANDNAND
0001
0101
1001
1110

NOR Gate

NOR is the complement of OR.

Y = (A+B)'
A B Y NOR
ABORNOR
0001
0110
1010
1110

XOR Gate

The XOR gate produces 1 when the two inputs are different.

Y = A ⊕ B
A B Y XOR
ABY=A⊕B
000
011
101
110

XNOR Gate

XNOR is the complement of XOR. It produces 1 when the inputs are the same.

Y = (A ⊕ B)'
A B Y XNOR
ABY
001
010
100
111

Logic Gate Summary

Gate Expression Output becomes 1 when...
AND A·B Both inputs are 1
OR A+B At least one input is 1
NOT A' Input is 0
NAND (A·B)' Inputs are not both 1
NOR (A+B)' Both inputs are 0
XOR A⊕B Inputs are different
XNOR (A⊕B)' Inputs are the same

5.14 Logic Gate Numerical and Output Problems

Example 31: Find the output of AND gate for A=1, B=0.
Y=A·B
Y=1·0
Y=0
Output = 0
Example 32: Find the output of OR gate for A=0, B=1.
Y=A+B
Y=0+1
Y=1
Output = 1
Example 33: Find NAND output for A=1, B=1.
AND output = 1·1 = 1
NAND output = (1)' = 0
Output = 0
Example 34: Find NOR output for A=0, B=0.
OR output = 0+0 = 0
NOR output = 0' = 1
Output = 1
Example 35: Find XOR output for A=1, B=0.
Inputs are different.
XOR output = 1
Example 36: Find XNOR output for A=1, B=1.
Inputs are the same.
XNOR output = 1

Combined Logic Expression Problems

Example 37: Find Y = A·B + C for A=1, B=0, C=1.
First calculate AND:
A·B = 1·0 = 0

Then OR with C:
Y = 0 + 1
Y = 1
Y = 1
Example 38: Find Y = (A+B)' for A=1, B=0.
A+B = 1+0 = 1
Y = 1' = 0
Y = 0
Example 39: Find Y = (A·B)' for A=1, B=0.
A·B = 1·0 = 0
Y = 0' = 1
Y = 1

5.15 Boolean Laws and De Morgan's Theorems

Boolean algebra is used to represent and simplify logical expressions.

LawExpression
IdentityA+0=A ; A·1=A
Null/DominanceA+1=1 ; A·0=0
IdempotentA+A=A ; A·A=A
ComplementA+A'=1 ; A·A'=0
Double complement(A')'=A
CommutativeA+B=B+A ; A·B=B·A
Associative(A+B)+C=A+(B+C)
DistributiveA(B+C)=AB+AC

De Morgan's Theorems

(A+B)' = A'·B'
(A·B)' = A'+B'

These laws are particularly important when explaining NAND and NOR operations and simplifying logic expressions.

NAND and NOR as Universal Gates

A universal gate is a gate from which the basic logic operations can be constructed. NAND and NOR are known as universal gates.

NOT using NAND

A NAND A = (A·A)' = A'

NOT using NOR

A NOR A = (A+A)' = A'

AND using NAND

A·B = [(A·B)']'

Therefore, first obtain NAND output and then invert it using another NAND gate with tied inputs.

OR using NAND

A+B = (A'·B')'

5.16 Large Numerical Practice Bank

The following practice set covers different patterns rather than repeating the same type of question.

Number System Conversion Practice

  1. Convert (37)10 to binary.
  2. Convert (89)10 to binary.
  3. Convert (127)10 to binary.
  4. Convert (255)10 to binary.
  5. Convert (101011)2 to decimal.
  6. Convert (11100101)2 to decimal.
  7. Convert (345)8 to decimal.
  8. Convert (672)8 to decimal.
  9. Convert (100)10 to octal.
  10. Convert (999)10 to octal.
  11. Convert (1A)16 to decimal.
  12. Convert (7B)16 to decimal.
  13. Convert (4095)10 to hexadecimal.
  14. Convert (2048)10 to hexadecimal.
  15. Convert (10110110)2 to octal.
  16. Convert (11111111)2 to hexadecimal.
  17. Convert (754)8 to binary.
  18. Convert (653)8 to binary.
  19. Convert (AB)16 to binary.
  20. Convert (F5)16 to binary.
  21. Convert (745)8 to hexadecimal.
  22. Convert (2D7)16 to octal.
  23. Convert (56.25)10 to binary.
  24. Convert (12.625)10 to binary.
  25. Convert (101.11)2 to decimal.
  26. Convert (1101.101)2 to decimal.
  27. Convert (0.75)10 to binary.
  28. Convert (0.875)10 to binary.
  29. Convert (0.625)10 to hexadecimal.
  30. Convert (0.5)10 to octal.

Binary Arithmetic Practice

  1. 1010 + 1101
  2. 1111 + 1010
  3. 10101 + 11111
  4. 110011 + 101101
  5. 111111 + 1
  6. 100101 + 11011
  7. 1101 − 101
  8. 10110 − 111
  9. 10000 − 1
  10. 110101 − 10111
  11. 1000000 − 1111
  12. 1110001 − 101101

Logic Gate Practice

  1. Construct the truth table for AND gate.
  2. Construct the truth table for OR gate.
  3. Construct the truth table for NAND gate.
  4. Construct the truth table for NOR gate.
  5. Construct the truth table for XOR gate.
  6. Construct the truth table for XNOR gate.
  7. Find output of A·B when A=1 and B=1.
  8. Find output of A+B when A=0 and B=1.
  9. Find output of (A·B)' for A=1 and B=0.
  10. Find output of (A+B)' for A=0 and B=0.
  11. Find output of A⊕B for A=1 and B=0.
  12. Find output of XNOR for A=0 and B=0.
  13. Explain NAND as universal gate.
  14. Explain NOR as universal gate.
  15. Prove De Morgan's first theorem using a truth table.
  16. Prove De Morgan's second theorem using a truth table.

Quick Conversion Reference Table

Conversion Best examination method
Decimal integer → Binary Repeated division by 2
Binary → Decimal Place-value expansion
Decimal integer → Octal Repeated division by 8
Octal → Decimal Place-value expansion
Decimal integer → Hexadecimal Repeated division by 16
Hexadecimal → Decimal Place-value expansion
Binary → Octal Group 3 bits
Octal → Binary Replace each digit with 3 bits
Binary → Hexadecimal Group 4 bits
Hexadecimal → Binary Replace each digit with 4 bits
Decimal fraction → another base Repeated multiplication
Fractional binary → decimal Use negative powers of 2

UNIT 6 – DATABASE MANAGEMENT SYSTEM

6.1 What is a Database?

A database is an organized collection of related data stored in a manner that allows the data to be accessed, managed and updated efficiently.

For example, a college may maintain a database containing student names, registration numbers, addresses, subjects, marks and attendance records.

Data and Information

Data are raw facts or observations. When data are processed and organized so that they become meaningful and useful, they become information.

Data Information
85, 72, 91 Student's examination marks
Rikrit, 23, Microbiology Organized student record

6.2 What is DBMS?

A Database Management System (DBMS) is software used to create, store, organize, retrieve, update and manage data in databases.

A DBMS acts as an interface between users/applications and the stored database.

User/Application → DBMS → Database

Major Functions of DBMS

  • Database creation
  • Data storage
  • Data retrieval
  • Data insertion
  • Data modification
  • Data deletion
  • Security and access control
  • Integrity management
  • Backup and recovery
  • Transaction management
  • Concurrent access management

6.3 Advantages of Database Approach

1. Reduced Data Redundancy

Centralized database management can reduce unnecessary duplication of the same data in different files.

2. Improved Data Consistency

When duplicated data are reduced and updates are centrally managed, the possibility of contradictory versions of data can be reduced.

3. Data Sharing

Multiple authorized users and applications can access shared data.

4. Data Security

Access controls can restrict data to authorized users.

5. Data Integrity

Rules and constraints can help maintain valid and accurate data.

6. Backup and Recovery

DBMS systems can provide mechanisms for backup and recovery after failures.

7. Data Independence

Data independence refers to the ability to modify aspects of data storage or schema without requiring unnecessary changes to application programs.

Database Applications

  • Banking systems
  • Hospital management
  • University and college systems
  • Library systems
  • Airline reservation
  • Government records
  • E-commerce
  • Scientific research
  • Telecommunication systems
  • Inventory management
  • Payroll systems
  • Biological databases

6.4 Introduction to Database Models

A database model defines how data are organized, related and represented in a database system.

1. Hierarchical Model

The hierarchical model organizes data in a tree-like structure consisting of parent-child relationships.

Root → Parent → Child → Sub-child

It is suitable for data having clear hierarchical relationships.

2. Network Model

The network model represents records using a network of relationships. It can represent more complex relationships than a simple tree.

3. Relational Model

The relational model stores data in tables consisting of rows and columns. It is one of the most widely used database approaches.

A row generally represents a record, while a column represents an attribute or field.

4. Object-Oriented Model

The object-oriented model represents information using objects and their associated properties and behavior.

Model Basic structure Main idea
Hierarchical Tree Parent-child relationships
Network Network/graph Multiple relationships
Relational Tables Rows and columns
Object-oriented Objects Objects and their properties/behavior

6.5 Data Warehouse, Data Mart and Data Mining

Data Warehouse

A data warehouse is a centralized repository designed mainly for storing and analyzing large amounts of data collected from different sources.

It is commonly used for reporting, analysis and decision-support activities.

Data Mart

A data mart is a smaller, subject-oriented portion of data designed to serve a particular department, function or user group.

For example, an organization may maintain separate sales, finance and human resource data marts.

Data Mining

Data mining is the process of discovering useful patterns, relationships, trends or knowledge from large datasets.

Common analytical tasks include classification, clustering, association analysis and prediction.

Concept Main purpose
Database Organized collection of data
DBMS Software for managing databases
Data warehouse Large repository for analysis/reporting
Data mart Department/subject-focused subset
Data mining Discovering patterns and knowledge

6.6 Computational Nanoscience

Computational nanoscience uses computational methods to model, simulate and analyze systems at the nanoscale.

It can help researchers study structures and behavior of materials and molecules when direct experimental observation or repeated experimentation may be difficult or expensive.

Applications

  • Nanomaterial modeling
  • Molecular simulation
  • Drug and material design
  • Nanostructure analysis
  • Prediction of material properties
  • Simulation of molecular interactions

Space Data

Space data refers to data collected from satellites, spacecraft, remote sensing systems, astronomical instruments and other space-based platforms.

Computational methods are used to store, process, visualize and analyze large volumes of space-related information.

Applications of space data

  • Earth observation
  • Weather and climate studies
  • Disaster monitoring
  • Land-use analysis
  • Ocean observation
  • Atmospheric studies
  • Astronomical research
  • Satellite image analysis

Computational Biology

Computational biology is an interdisciplinary field that uses computational techniques to solve biological problems and analyze biological data.

It combines biology with computation, statistics and mathematical approaches.

Major areas

  • DNA sequence analysis
  • RNA analysis
  • Protein sequence analysis
  • Genome analysis
  • Comparative genomics
  • Phylogenetic analysis
  • Protein structure prediction
  • Biological database analysis
  • Drug discovery
  • Molecular modeling

Importance of Computational Biology

Modern biological research generates extremely large datasets. Computational methods allow researchers to store, organize, compare and analyze such data more efficiently than manual methods.

Relationship Among Database, Data Warehouse and Data Mining

Data Sources → Database/Data Collection → Data Warehouse → Data Mining → Knowledge/Patterns

The relationship is not necessarily a single compulsory architecture in every system, but the sequence illustrates a common analytical workflow.

6.7 Important TU-Style Questions

10-Mark Questions

  1. Define DBMS and explain its functions and advantages.
  2. What is a database? Explain the database approach and its advantages.
  3. Explain different database models with suitable examples.
  4. Discuss data warehouse, data mart and data mining.
  5. Write an essay on computational biology and its applications.
  6. Explain the role of computational methods in nanoscience and space data.

5-Mark Questions

  1. Define DBMS and mention its major functions.
  2. Explain the relational database model.
  3. Write a short note on data mining.
  4. What is a data warehouse?
  5. Differentiate data warehouse and data mart.
  6. Write a short note on computational biology.
  7. Write a short note on computational nanoscience.
  8. What is space data?

2-Mark Questions

  • Define database.
  • Define DBMS.
  • What is data redundancy?
  • What is data independence?
  • What is a relational model?
  • What is data mining?
  • What is a data warehouse?
  • What is a data mart?
  • Define computational biology.
  • What is computational nanoscience?

FINAL SECTION 2 REVISION

Unit 4 – Must Remember

  • Definition of Internet
  • Internet as a network of networks
  • E-mail
  • FTP
  • Telnet
  • Usenet News
  • WWW
  • Internet uses
  • IP address
  • Domain name
  • URL and its components
  • Internet vs WWW

Unit 5 – Must Practice

  • All four number systems
  • Decimal ↔ Binary
  • Decimal ↔ Octal
  • Decimal ↔ Hexadecimal
  • Binary ↔ Octal
  • Binary ↔ Hexadecimal
  • Octal ↔ Hexadecimal
  • Fractional conversion
  • Mixed-number conversion
  • Binary addition
  • Binary subtraction
  • AND, OR, NOT
  • NAND, NOR
  • XOR, XNOR
  • Truth tables
  • Boolean expressions
  • Universal gates
  • De Morgan's laws

Unit 6 – Must Remember

  • Database
  • DBMS
  • Database approach
  • Advantages of DBMS
  • Database applications
  • Hierarchical model
  • Network model
  • Relational model
  • Object-oriented model
  • Data warehouse
  • Data mart
  • Data mining
  • Computational nanoscience
  • Space data
  • Computational biology

How to Write a Numerical in TU Examination

  1. Write the question clearly.
  2. Write the required conversion/operation.
  3. Show the calculation steps.
  4. Do not skip important remainders or carries.
  5. For grouping questions, show the groups.
  6. For fractional conversions, show every multiplication.
  7. Write the final answer with the correct base.
  8. Check the answer if sufficient time remains.
Final exam reminder: For Unit 5, the examiner is not only interested in whether the final number is correct. A properly presented calculation allows the examiner to see the method. Therefore, avoid writing only the final answer. Show the working clearly.

High-Priority Long Questions

  1. Explain the Internet and discuss its major services.
  2. Explain Internet addressing with IP address, domain name and URL.
  3. Explain different number systems with suitable examples.
  4. Describe different methods of number-system conversion with examples.
  5. Solve different numerical problems involving binary, octal, decimal and hexadecimal systems.
  6. Explain binary addition and subtraction with suitable examples.
  7. Explain different logic gates with symbols, Boolean expressions and truth tables.
  8. Explain NAND and NOR gates as universal gates.
  9. State and verify De Morgan's laws using truth tables.
  10. Define database and DBMS and explain the advantages of the database approach.
  11. Explain different database models.
  12. Differentiate data warehouse, data mart and data mining.
  13. Discuss applications of computational biology.