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CHAPTER 1:FUNDAMENTALS OF DATABASE MANAGEMENT SYSTEM, Nur Naziha Binti…
CHAPTER 1:FUNDAMENTALS OF DATABASE MANAGEMENT SYSTEM
1.1 UNDERSTAND DATABASE
data base is
a collection of relative data shared by various categories of users to fulfill the information needs and requirements of an organization
a database application is a program application written in a specific programming language
database in every day in life
example:
online TV streaming
social gaming
E-commerce
social media
finances
importance of database to everyday life
a database can be used at once is shared by many users
perform protection and data security
overcoming difficult in accessing data
control of data redundancy
provision for multiple views of data
-enforcement of integrity constrains
uses of database in business world
database are powerful organizational tools that help businesses quickly record, view and respond to important information . when used effectively , they can improve that efficiency and profitability of a business
example of database role in business world :
customer relational management
inventory tracking
personnel database
analyse
properties of data base
completeness ensure that users can access the data they want .
integrity ensure that data is both consistent and correct and ensures that users trust the database
flexibility ensures that a database can evolve to satisfy changing users requirements
efficiency ensure that users do not have unduly long response times when accessing data
usability ensure that data can be accessed and manipulated in ways which match user requirement
1.2 UNDERSTAND DBMS
-Definition: A software system which enables user to define, create, organize, update, manage and administer databases.
-DBMS also controls access to data in a database.
-Example: MS access, Oracle, MySQL, Filemaker.
Users of DBMS
-
End user
are the people who use the application programs to run the organization's daily operations.
-Example, sales clerks, supervisors, managers and directors are all classified as end users.
-
Application programmer
is an individual who writes application programs in a user organization
-
Data administrator
manage the DBMS and ensure that the database is functioning properly
-Database system attempts to solve the difficulties in conventional file processing system.
-Example:
Data redundancy and inconsistency ,Data isolation, Integrity problems, Atomicity problems
Disadvantages of traditional approach to information processing :
1) Data Isolation
-Data Isolation means that all the related data is not available in one file.
2) Lack of flexibility
-The traditional systems are able to retrieve information for predetermined requests for data.
-By the time the information is made available, it may no longer be required or useful.
3)Program/data dependence:
-In traditional file approach ,application programs are closely dependent on the files in which data is stored.
-If we make any changes in the physical format of the file(s), like addition of a data field, all application programs needs to be changed accordingly.
4)Concurrent access anomalies
-Many traditional systems allow multiple users to access and update the same piece of data simultaneously.
-However this concurrent updates may result in inconsistent data.
The importance of having DBMS:
1)Controlling Redundancy
2)Integrity can be enforced
3)Inconsistency can be avoided
4)Data can be shared
5)Standards can be unforced
Database architecture:
-Two generic database architecture
1)Centralized database
~all the data of an organization is stored in a single place such as a mainframe computer or a server.
2)Distributed database
~In a distributed database ,the data is stored in storage devices that are located in different physical locations.
1.3 UNDERSTAND DATA MODEL
Data model is an integrated collection of concepts for describing and manipulating data, relationships between data and constraints on the data in the organization.
A model is a representation of real-world objects and events, and their association.
A data model represents the organization itself.
Object based data models
are based on above concept.
It is designed using the entities in the real world, attributes of each entity and their relationship.
Record based logical models
are used in describing data at the logical and view levels.
In contrast to object based data models, they are used to specify the overall logical structure of the database and to provide a higher-level description of the implementation.
Record based models are so named because the database is structured in fixed format records of several types. Each record type defines a fixed number of fields, or attributes, and each field is usually of a fixed length.
The Hierarchical model represents data as a hierarchical tree structures. Each hierarchy represents a number of related records.
The Network model represents data as record types and also represents a limited type of one to many relationship, called set type.
Relational data model: data and relationships are represented by a collection of tables.
THREE-SCHEMA ARCHITECTURE OF DBMS
ANSI-SPARC (American National Standard Institute – Standard Planning and Requirements Committee) proposed a 3 schema architecture.
The goal of the three-schema architecture is to separate the user applications and the physical database.
External Level
User’s view of the DB where only a part of the database is suitable to the requirements of each user
Conceptual Level
The middle level between the external and the internal levels.
Supports the external scheme where any data useful to users need to be stated in this level.
Represent a complete organizational environment.
Internal Level
Lowest Level of ANSI/SPARC and closest to a DB.
Explain how data is stored in a database.
Covers physical implementation of the DB for optimum runtime and data structure/file organization used to store data in storage instrument.
CLIENT-SERVER ARCHITECTURE OF DBMS
Client Server
DBMS is located in a computer called server.
Has very high processing capabilities.
Its acts as a monitor to other clients computers connected to it in a local area network.
Server computer is known as the ‘backend’ whereas the client computer acts as the ‘front-end’.
Capable of reducing cost because users are able to use personal computers or workstations as server and client
Able to share resources such as scanner, printers etc.
Desktop databases
offer simple, flexible solutions for data storage and retrieval.
They're often quite sufficient to meet uncomplicated database requirements for both small and large organizations.
BENEFITS OF USING DESKTOP DATABASE SOLUTION
-Easy Management
-Low Running Costs
-Easy To Use
Server Database
Some examples of Database servers are Oracle, DB2, and SQL Server.
Every server uses its own query logic and structure.
The SQL query language is more or less the same in all the database servers.
BENEFITS OF USING SERVER DATABASE SOLUTION
-Scalability
-Wider integration
-Desktop management
Nur Naziha Binti Abdullah Saji