database system

1. Jimma University
Institute of Technology
School of computing
Fundamentals of Database systems

2. CHAPTER ONE
Introduction:
Databases and Database Users

3. Chapter one
Chapter Objectives
At the end the chapter students should able to know:
 The meaning of the term ‘database’.
 The meaning of the term ‘database management system’
(DBMS).
 Some common uses of database systems.
 The characteristics of Database systems.
 The problems with the file-based approach.
 The typical functions of a DBMS.
 The major components of the DBMS environment.
 The history of the development of DBMSs.
 The advantages and disadvantages of DBMSs.

4. Definitions
 Database
is a collection of related data.
 Data
is a collection of facts and figures that can be processed to produce
information.
 Database Management System or DBMS
 in short refers to the technology of storing and retrieving users’
data with utmost efficiency along with appropriate security
measures.
 A software package/ system to facilitate the creation and
maintenance of a computerized database.
 stores data in such a way that it becomes easier to retrieve,
manipulate, and produce information.

5.  Database System:
 The DBMS software together with the data itself. Sometimes, the
applications are also included.

6. Simplified database system environment
.
Figure 1.1. Simplified database system environment

7. Characteristics-
DBMS was a new concept then, and all the research was done to
make it overcome the deficiencies in traditional style of data
management.
1. Real-world entity − A modern DBMS is more realistic and
uses real-world entities to design its architecture.
 It uses the behavior and attributes too.
 For example, a school database may use students as an
entity and their age as an attribute.
2. Relation-based tables − DBMS allows entities and relations
among them to form tables.
A user can understand the architecture of a database just by
looking at the table names.

8. 3. Isolation of data and application − A database
system is entirely different than its data.
A database is an active entity, whereas data is said to be
passive, on which the database works and organizes.
DBMS also stores metadata, which is data about data, to ease its own
process.
4. Less redundancy − DBMS follows the rules of normalization,
which splits a relation when any of its attributes is having
redundancy in values.
Normalization is a mathematically rich and scientific process that
reduces data redundancy.

9. 5. Consistency− Consistency is a state where every relation
in a database remains consistent.
There exist methods and techniques, which can detect
attempt of leaving database in inconsistent state.
A DBMS can provide greater consistency as compared to
earlier forms of data storing applications like file-processing
systems.
6. Query Language − DBMS is equipped with query language,
which makes it more efficient to retrieve and manipulate data.
A user can apply as many and as different filtering options as
required to retrieve a set of data.
Traditionally it was not possible where file-processing system was
used.

10. 8. ACID Properties − DBMS follows the concepts
of Atomicity, Consistency, Isolation, and Durability (normally
shortened as ACID). These concepts are applied on transactions, which
manipulate data in a database.
 Atomicity − is, either all of its operations are executed or none.
 Consistency − No transaction should have any adverse effect on the
data residing in the database.
 Isolation − No transaction will affect the existence of any other
transaction.
 Durability − The database should be durable enough to hold all its
latest updates even if the system fails or restarts.

11. 9. Multiuser and Concurrent Access − DBMS supports
multi-user environment and allows them to access and manipulate
data in parallel.
10.Multiple views − DBMS offers multiple views for different
users. A user who is in the Sales department will have a different view
of database than a person working in the Production department.
11. Security − Features like multiple views offer security to some
extent where users are unable to access data of other users and
departments.
DBMS offers many different levels of security features, which enables
multiple users to have different views with different features.

12. Typical DBMS Functionality
 Define a particular database in terms of its data types,
structures, and constraints
 Construct or Load the initial database contents on a
secondary storage medium
 Manipulating the database:
 Retrieval: Querying, generating reports
 Modification: Insertions, deletions and updates to its content
 Accessing the database through Web applications

13. Cont…
Processing and Sharing by a set of concurrent users
and application programs –yet, keeping all data valid
and consistent
Other features:
 Protection or Security measures to prevent unauthorized
access
 Active processing to take internal actions on data
 Presentation and Visualization of data
 Maintaining the database and associated programs over the
lifetime of the database application Called database, software,
and system maintenance

14. Example of a Database
(with a Conceptual Data Model)
Example:
 UNIVERSITY Database
Some entities:
 STUDENTs
 COURSEs
 SECTIONs (of COURSEs)
 (academic) DEPARTMENTs
 INSTRUCTORs

15.  Some relationships:
 SECTIONs are of specific COURSEs
 STUDENTs take SECTIONs
 COURSEs have prerequisite COURSEs
 INSTRUCTORs teach SECTIONs
 COURSEs are offered by DEPARTMENTs
 STUDENTs major in DEPARTMENTs
* Note: The above entities and relationships are typically
expressed in a conceptual data model, such as the ENTITY-
RELATIONSHIP data model.

16. File-based System: 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.
Traditionally, data was organized in file formats.
Disadvantage
 Separation and isolation of data
 Duplication of data and inconsistency
 Data dependence
 Incompatible file formats
 Fixed queries/proliferation of application programs
 Difficulty in accessing data
 Integrity problems
 Atomicity problems
 Concurrent-access anomalies
 Security problems

17.  What is table?
 The data in DBMS is stored in database objects called tables.
 The table is a collection of related data entries and it consists
of columns and rows.

18.  What is field?
 Every table is broken up into smaller entities called fields. The fields in the
CUSTOMERS table consist of ID, NAME, AGE, ADDRESS and SALARY.
A field is a column in a table that is designed to maintain specific
information about every record in the table.
 What is record or row?
A record, also called a row of data, is each individual entry that exists in a
table
A record is a horizontal entity in a table.

19. What is column?
 A column is a vertical entity in a table that contains all
information associated with a specific field in a table.
 For example, a column in the CUSTOMERS table is ADDRESS,
which represents location description and would consist of the
following:

20. Users
A typical DBMS has users with different rights and permissions who use
it for different purposes.
Some users retrieve data and some back it up.
 The users of a DBMS can be broadly categorized as follows −

21. I. Administrators − Administrators maintain the DBMS and are
responsible for administrating the database.
 responsible to look after its usage and by whom it should be used.
 Can create access profiles for users and apply limitations to
maintain isolation and force security.
 Look after DBMS resources like system license, required tools, and
other software and hardware related maintenance.
II. Designers − are the group of people who actually work on the
designing part of the database.
 Keep a close watch on what data should be kept and in what
format.
 Identify and design the whole set of entities, relations, constraints,
and views.

22. III.End Users − End users are those who actually reap the
benefits of having a DBMS.
 End users can range from simple viewers who pay attention to
the logs or market rates to sophisticated users such as business
analysts.
 Categories of End-users
 Casual: access database occasionally when needed
 Naïve or Parametric: they make up a large section of the end-user
population.
 They use previously well-defined functions in the form of
“canned transactions” against the database.
 Examples are bank-tellers or reservation clerks who do this
activity for an entire shift of operations.

23.  Sophisticated:
 These include business analysts, scientists, engineers, others
thoroughly familiar with the system capabilities.
 Many use tools in the form of software packages that work
closely with the stored database.
 Stand-alone:
 Mostly maintain personal databases using ready-to-use
packaged applications.
 An example is a tax program user that creates its own internal
database.
 Another example is maintaining an address book

24. Historical Development of Database Technology
 Early Database Applications:
 The Hierarchical and Network Models were introduced in mid
1960s and dominated during the seventies.
 A bulk of the worldwide database processing still occurs using
these models.
 Relational Model based Systems:
 Relational model was originally introduced in 1970, was
heavily researched and experimented with in IBM Research
and several universities.
 Relational DBMS Products emerged in the 1980s.

25. Historical Development of Database Technology
 Object-oriented and emerging applications:
 Object-Oriented Database Management Systems (OODBMSs)
were introduced in late 1980s and early 1990s to cater to the
need of complex data processing in CAD and other
applications.
 Their use has not taken off much.
 Many relational DBMSs have incorporated object database
concepts, leading to a new category called object-relational
DBMSs (ORDBMSs)
 Extended relational systems add further capabilities (e.g. for
multimedia data, XML, and other data types)

26. Historical Development of Database Technology
 Data on the Web and E-commerce Applications:
 Web contains data in HTML (Hypertext markup language)
with links among pages.
 This has given rise to a new set of applications and E-
commerce is using new standards like XML (extended
Markup Language).
 Script programming languages such as PHP and JavaScript
allow generation of dynamic Web pages that are partially
generated from a database
 Also allow database updates through Web pages

27. Applications
 Traditional Applications:
 Numeric and Textual Databases
 More Recent Applications:
 Multimedia Databases
 Geographic Information Systems (GIS)
 Data Warehouses
 Real-time and Active Databases
 Many other applications

28. a) BANKING: For customer ,information, account, loans, and
transaction.
b) Airline: For reservation and schedule information. Airline were
among the first to use database in a geographically distributed
manner terminals situated around the world accessed the central
database system through phone lines and other data network.
c) Universities: For students information, course registration, and
grades.
d) Credits card transaction: For purchases on credits cards and
generation of monthly statements.
e) Sales: For customer, product, and purchase information.
f) Human resources: For information about employees, salaries,
payroll taxes and benefits, and for generation of paychecks.

29. When not to use a DBMS
 Main inhibitors (costs) of using a DBMS:
 High initial investment and possible need for additional
hardware.
 Overhead for providing generality, security, concurrency
control, recovery, and integrity functions.
 When a DBMS may be unnecessary:
 If the database and applications are simple, well defined, and
not expected to change.
 If there are stringent real-time requirements that may not be
met because of DBMS overhead.
 If access to data by multiple users is not required.

30. When not to use a DBMS
 When no DBMS may suffice:
 If the database system is not able to handle the complexity of
data because of modeling limitations
 If the database users need special operations not supported by
the DBMS.

31. Summary
Types of Databases and Database Applications
Basic Definitions
Typical DBMS Functionality
Example of a Database (UNIVERSITY)
Main Characteristics of the Database
Database Users
Advantages of Using the Database Approach
When Not to Use Databases