18-03-2011, 09:34 AM
Presented by:
Mohammad Waqar
Umair Maqbool
Kashif Baloch
Kazim Raza Rizvi
Mohammad Shahzad
Muzammil Shah
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Objective
Introductory Database Concepts
Data Warehouse and Data Mining
Role in the Integrated Database Environment
Database System Environment
Database Models
Data Dictionary
Three Level Architecture
Data Independence
Data vs. Information
Data
Data is unprocessed information
Information
Data that have been organized and communicated in a meaningful manner
Data to Information Benefit
Three basic benefits of Data to Information:
Information reveals meaning of data
Good, Timely, relevant information key to decision making
Good decision making key to organization survival
Introduction
What is Database?
A database is any organized collection of data Some examples of databases you may encounter in your daily life are:
A Telephone Book
T.V. Guide
Airline Reservation System
Motor Vehicle Registration Records
Files on your Computer Hdd.
Difference between Database and DBMS?
Database
Organized collection of related data
Ex. Names, Telephone numbers and Addresses of all the people you know
DBMS
A computerized record-keeping system
It is a set of computer program that controls the creation, maintenance and the use of database. Database development in the hand of DBA and other specialists
Data Warehouse
Data warehouse is a powerful database model that significantly enhances the users ability to quickly analyze large multidimensional data set
It organizes data to allow user to make business decisions
A set of new concept and tools has evolved into a new technology that addresses the problems of providing all key people with access to information needed for the enterprise to survive and prosper in increasingly competitive world
Date warehousing is a field that has grown form the integration of a number of different technologies and experiences over the past two decades
Why A Data Warehouse?
Everyday organizations large and small create billions of bytes of data about all aspects of their business. Millions of individuals facts about their customers, products, operations, and people but for the most part this is locked up in a maze of computer system and exceedingly difficult to get at. This Phenomenon has been described as “data in jail”
Data Mining
It is a technique of organizing meaningful information from large and unorganized data banks
Organizations generate large amount of data that is unorganized. This data requires processing to be done to generate meaningful information to organize this data we use DBMS but it is not always adequate to meet end user requirements form on large data banks
What is the ultimate purpose of a database management system?
Is to transform
File System Critiques
File System Data Management
Time consuming
Make ad hoc quires impossible
Leads to island of information
Data inconsistency & redundancy
Data dependence & structural dependence
Database vs. File System
Historical Perspective
Earliest days 1960s
The 1st general purpose DBMS was design by Charls Bachman at general electric in the early 1960s and was called integrated data store it formed for the network data model
In the late 1960s IBM developed IMS (Information Management system)
In 1970s Edgar cod IBMS in San Jose Research lab proposed a new data representation frame called relational data model
In the late 1980s advances have made in many areas of database system
Goals of a DBMS
To provide an efficient as well as a convenient environment for accessing data in a database
Remove Difficulty in accessing data
Enforce information security in database, concurrency & redundancy control, crash recovery
Reduce application development time
Uniform data Administration
Multi users access control
Why do we need a database?
Keep records of our:
• Clients
• Staff
• Volunteers
To keep a record of activities and interventions
Keep sales records
Develop reports
Perform research
Longitudinal tracking
Role in the integrated database environment
Many individual and groups involved in operations, having different role depending on the way they interact with database
End Users
Application Programmers
Database Administrator
End users
Database designs, created and maintained to serve the information need of End Users
User categorized:
Sophisticated user (Casual User)
They are trained in use of online Query language and access data by entering queries at the terminal
Naive User
They access the data through application programs
Application PROGRAMMERS
Application Programmers are responsible for writing application programs that use the database. These programs could be written in General Purpose Programming languages such as Visual Basic, C, FORTRAN, COBOL etc.
Database administrator
The DBA is a person or a group of persons who is responsible for the management of the database
DBA is responsible for:
Authorizing access to the database
Coordinating and monitoring its use
managing backups
Repairing damage due to hardware or software failures and its need
DBMS Users Interaction
Database System Environment
Database Models
Collection of logical constructs used to represent data structure and relationship within the database
To manage data as a resource
For the integration of Information System (IS)
For designing database/data warehouse
Semantic data model
Entity Relationship model (ER Model)
Record based model
The Relational Model
Hierarchal model
The Network Model
Entity relationship model (er model)
Proposed by Peter Chen in 1970s
The ER Data Model views the real world as a set of basic objects (entities) and there attributes and relationships among these objects.
Provide a graphical method for depicting the logical structure of database
Entity
An Entity is an object that exists and distinguishable from other objects
Attribute
Attribute of an entity set are the defining properties or qualities of the entity type
Relationship
A set of relationship of same type and we add fact the relationship may themselves have descriptive attribute
Graphical method of ER Model
Student
StuName Attribute to entity
Enroll
Line Link Entity set to Relationship set
Attribute to Relationship set
Hierarchal Database Model
Logically represented by an upside down tree
• Each parent can have many children
• Each child has only one parent
Network Database Model
Each record can have multiple parents
• Composed of sets
• Each set has owner record and member record
• Member may have several owners
Relational Database Model
Perceived by user as a collection of tables for data storage
Tables are a series of row/column intersections
Tables related by sharing common entity characteristic(s)
Data Dictionary
It is a repository of information that describe the logical structure of the database
It has entries from record type, data type, data aggregates and other information
Store database schema but can be used in creating and processing database
Contains metadata
If part of DBMS then called integrated data dictionary
Communicate with user for exact meaning store
Helps in retrieving information on call
Three Level Architecture
Purpose
Is to separate the way the database is physically represented from the way user think about it. Different reasons are there:
User’s view
Different users need different views of the same data
The way a particular user needs to see the data may change over time
Cont.
Dba's view
The DBA should be able to change the overall logical structure of the database without affecting all users
The DBA should be able to change data and file structure of database without affecting all users
Database structure should be unaffected by the changes to the physical aspects of storage, such as changes to the storage devices
Three Level Architecture
External View or Model
The way the user think about data, called the External View Level
User’s point of view
External level consists of many different external views
Each external view may have different representations
External views are described in External schemas which are written in the Data Definition Language
Each user’s schema provides complete description of user’s view
External sachems are used to create GUI
Continue
User only interact with certain entities
User will be unaware of other entities, attributes and relationships
Conceptual or Logical Model
DBA’s point of view
Middle level that contains entire information of the database
Community view of the database.
Complete model of working organization
Complete logical model
Entities, attributes, relationships, constraints on data, semantic information, security and integrity
Conceptual model supports external views
Conceptual model is relatively constant
DBA is responsible to design it
Conceptual model can be extended
It is written in DDL, stored in Data Dictionary and compiled by DBMS, using DML
Physical Model
Describe how the data stored in the database
Physical implemetati0n of database
Include data structure and file organization
Works with operating system
To layout data on the storage devices
Build indexes
Set the pointers
Simply, it is managed by OS under the instruction of DBMS
Mapping b/w logical and physical model
Stores in data dictionary
Three Level Architecture
Data Independence
The disjointing of data description from the application program (or user interface) that uses the data, data independence
Three Level of Architecture provide the concept of Data Independence
Means that
upper levels are unaffected by bringing changes in the lower level
Types of Data Independence
There are two types
Logical data independence
The ability to modify conceptual schema or model without causing application program rewritten
Should not required changes to external schema or model
Usually done when logical structure of database is altered
Physical data independence
Refers to immunity of conceptual schema to changes in the internal schema
Internal schema changes (e.g. using different file organization, storage structure/devices)
If someone changes his HDD from FAT32 to NTFS
Modification at this level are usually to improve performance