1. ETEC 100 Information Technology
Lecture
Introduction to database

2. Learning Objectives
Define and understand the following terms: data, information, database, database management system (DBMS), database system, metadata
Compare and contrast conventional file systems and database systems. Identify advantages of database approach over traditional file systems

3. What is database?
Database: An organized collection of logically related data
Data: Known facts that could be recorded and stored on computer media
Facts could be in any format: text, graphics, images…
Information: Processed data that could be used to increase the knowledge of the user
Closely related to data, but different
View data as “raw material” and information as “intermediate product”
The final product is “knowledge”

4. Data, Information and Knowledge
A. Berger
M. Jones
T. Martin
J. Smith
Shoes
Scarves
Jewelry
Groceries
A. Berger is most
likely to buy new
product
John Smith
Taurus
Database Queries ?
wireless
50,000
234
Ted Martin
Amex Gold
Anna Berger
50,000
46,800
29,200
75,500
MoU
Qty
Income
Education
B.A.
T. Martin is profitable
customer and is likely
to switch carriers
shoes
Data
Information
Knowledge &
Customer Insight
Some of the images above come from a presentation given by:

5. Databases Interact with DBs many times in a day
Database processing integral part of many businesses
Keep track of things (what sort of things?)

6. History of data collection methods
Manual System
File System
Database System

7. Manual Filling Systems
Before computer: Manual Filing Systems
Still used in many everyday activities
Usually organize data in a logical way
Ex;bills……..
Problems with Manual Filling Systems
Small –scale
Hard to analyze: ‘ How many students enrolled in MIS ?

8. Traditional File-Based processing
Application programs were written specifically for the data file structure that was to be used, so:
A change in the data file structure required change in an application program(s) that needed that data

10. File Processing Systems: An example
Data Entry
End Users
File Management Programs
File Report Programs
Data Files
Separated systems, separated files, separated data
Both file management programs and file report programs have describe WHAT data to write / read and HOW to do that

11. File Processing Systems: Problems
Isolation of Data/ Limited Data Sharing
Isolation between departments file systems
Isolation in a department file system:
Duplication of Data
Duplicated data waste storage space
Duplicated data result in loss of data integrity
Lack of Data Independence
If we change the data type of address from 40 characters to 41 characters, all related programs have to change accordingly

12. Database Systems: Basic Terms
Database: An organized collection of logically related data
Database Management Systems (DBMS): A software package to facilitate the creation and maintenance of a database.
Database system: a computerized record-keeping system, containing database and DBMS as well as some other components.
Four components: Users, Software, Hardware, Data

13. Database Systems: Basic Terms
End users
Software
interact
Application Programmers
Application Programs
develop
“What” to get
Database Administrators
DBMS
maintain
“How” to get
Data
Database Designers
design
Database
Users

14. Database Systems: Advantages
Data are stored in a central repository, managed by DBMS
Data sharing is easy
Reduce duplication to minimum: one table for each entity
Inconsistency can be avoided to some extent by enforcement of integrity constraints
Metadata offers data abstraction
Data independence: If format needs to be changed, simply update the metadata. Application programs are not affected
Structural independence: similar to the above

15. Data Elements in a Database
User data (files)
relations in a table format (e.g. Relational Database)
Metadata (systems tables)
data about data, data dictionary
meaning of terms, description of structure etc.
Indexes (overhead data)
improves performance and accessibility
Application Metadata
structure & format of forms, reports, & queries etc.

16. Database Development Process
Requirement Analysis
Conceptual Design
Logical Design
Physical Design
Implementation
Maintenance

17. Database Development Process
Requirements Analysis
Collect and Analyze the requirements of the users.
Conceptual Design
Design a conceptual model, e.g., ER model.
Logical Design
Translate the conceptual model into the logical model
Normalization.
Physical Design
Define the database and write application programs.
Implementation
Write, test, and install programs that process the database
MaintenanceUse
maintain, and “tune” the database

18. Relational Database
A relational database is one in which the data consists of a collection of tables related to each other through common values.
The two most prominent characteristics of a relational database are
data stored in tables
relationships between tables

19. Table

20. Relation Two-dimensional table Rows are tuples Columns are attributes
Equivalent Terms:

21. Characteristics of a relation
a relation has a unique name within same DB
each cell contains one single value
each attribute within a given relation has a distinct name
values of an attribute are from the same domain
order of attributes has no significance
order of rows has no significance
no duplicate rows

22. Key
“a group of one or more attributes (columns) that uniquely identifies a tuple (row)”

23. Relational Database Keys
Candidate key
Primary key: candidate key selected to uniquely identify all table rows
Foreign key: attributes(s) in one table whose values must match primary key in another table

24. Relationships

25. Referential Integrity Rule
If a foreign key exists in a relation,
either
the foreign key value must match a candidate key value of some tuple in its home relation or
the foreign key value must be wholly null
Therefore:- if B references A then A must exist

26. Schema
A schema is an abstract representation of database entities and objects. A schema helps us design a database diagrammatically before we start creating it.

27. Schema (cont.)

28. Query
Requests for information from a database are made in the form of a query.
The set of rules for constructing queries is known as a query language.
query language called SQL (structured query language)
For example, the query -requests all recordsfrom customer table in which the NAME field is SMITH and the AGE field is greater than 35.

29. SQL (structured query language)
For example, the query -requests all recordsfrom customer table in which the Name field is SMITH and the Age field is greater than 35.
SELECT ALL
FROM Customer
WHERE Name = "SMITH" and age > 35