Intro to Database

Question 1

What is Data?

Answer 1

Data is a raw facts that need to be processed in order to become an information.

Question 2

Types of Data

Answer 2

1. Numbers
2. Letters
3. Images
4. Audio
5. Videos

Question 3

Data vs. Information

Answer 3

 Data are raw facts
 Information is the result of processing
raw data to reveal meaning
 Information requires context to reveal
meaning
 Raw data must be formatted for storage, processing, and presentation
 Data are the foundation of information, which is the bedrock of knowledge
 Data: building blocks of information
 Information produced by processing data
 Information used to reveal meaning in data
 Accurate, relevant, timely information is
the key to good decision making
 Good decision making is the key to organizational survival

Question 4

What is the database?

Answer 4

A collection of related data. It is often abbreviated DB. It is a collection of information organized in such a way that a computer program can quickly select desired pieces of data.

Question 5

Databases can be classified according to what?

Answer 5

◦ Number of users
◦ Database location(s)
◦ Expected type and extent of use

Question 6

Single-user database

Answer 6

supports only one user at a time

Question 7

Multiuser database

Answer 7

supports multiple users at the same time

Question 8

Desktop database

Answer 8

single-user, runs on PC

Question 9

Workgroup database

Answer 9

supports a small number

Question 10

Enterprise database

Answer 10

supports a large number

Question 11

Type of single-user database

Answer 11

Desktop database

Question 12

Types of multiuser database

Answer 12

1. Workgroup database

2. Enterprise database

Question 13

Centralized database

Answer 13

data located at a single site

Question 14

Distributed database

Answer 14

data distributed across several different sites

Question 15

Operational database

Answer 15

supports a company’s day-to-day operations

Question 16

Types of operational database

Answer 16

Transactional or production database

Question 17

Data warehouse

Answer 17

stores data used for tactical or strategic decisions

Question 18

Types of databases

Answer 18

1. Single-user database
2. Multiuser database
3. Centralized database
4. Distributed database
5. Operational database
6. Data warehouse

Question 19

What is a database design?

Answer 19

Database design focuses on design of database structure used for end-user data

Question 20

What must the designer identify with the database?

Answer 20

◦ Designer must identify database’s expected use

Question 21

Well-designed database

Answer 21

◦ Facilitates data management

◦ Generates accurate and valuable information

Question 22

Poorly-designed database

Answer 22

◦ Causes difficult-to-trace errors

Question 23

Traditional File-Based Systems

Answer 23

A collection of application programs that perform services for the end users such as the production of reports. Each program defines and manages its own data.

Question 24

Limitations of a Traditional File-Base Systems

Answer 24

Limitations:

1. Separation & isolation of data
2. Duplication of data
3. Data dependence
4. Incompatibility of files

Question 25

Reasons for Studying File Systems

Answer 25

◦ Complexity of database design easier to understand ◦ Understanding file system problems helps to avoid problems with DBMS systems ◦ Knowledge of file system useful for converting file system to database system

Question 26

Historical Roots: Files and Files Systems

Answer 26

1. File systems typically composed of collection of file folders, each tagged and kept in cabinet ◦ Organized by expected use 2. Contents of each file folder logically related 3. Manual system served as a data repository for small data collections ◦ Cumbersome for large collections 4. Data processing (DP) specialist converted computer file structure from manual system ◦ Wrote software that managed the data ◦ Designed the application programs 5. Initially, computer files systems resembled manual systems 6. As number of files increased, file systems evolved ◦ Each file used its own application program to store, retrieve, modify data ◦ Each file owned by individual or department that commissioned its creation 7. Data processing (DP) manager supervised the DP department 8. DP department’s primary activity remained programming

Question 27

Problems with File System Data Management

Answer 27

1. Security features difficult to program ◦ Often omitted in file system environments 2. Summary of file system limitations: ◦ Requires extensive programming ◦ Can not perform ad hoc queries ◦ System administration complex and difficult ◦ Difficult to make changes to existing structures ◦ Security features likely to be inadequate

Question 28

Structural dependence

Answer 28

- access to a file dependent on its own structure ◦ All file system programs must be modified to conform to a new file structure

Question 29

Structural independence

Answer 29

change file structure without affecting data access

Question 30

Data dependence

Answer 30

data access changes when data storage characteristics change

Question 31

Data independence

Answer 31

data storage characteristics do not affect data access

Question 32

Data redundancy

Answer 32

 File system structure makes it difficult to combine data from multiple sources ◦ Vulnerable to security breaches  Organizational structure promotes storage of same data in different locations ◦ Islands of information  Data stored in different locations unlikely to be updated consistently  Data redundancy: same data stored unnecessarily in different places

Question 33

Data inconsistency

Answer 33

different and conflicting versions of same data occur at different places

Question 34

Data anomalies

Answer 34

abnormalities when all changes in redundant data not made correctly ◦ Update anomalies ◦ Insertion anomalies ◦ Deletion anomalies