Transcript Introduction to Database

College Of Science & Technology- Khan younis
Information Technology & Computer Science Dep.
Database Management System
Part 1
The Database Environment
Prepared by
Dr. Ahmed El-Ragal
Reviewed & Presented By
Mr. Mahmoud Rafeek Alfarra
Definitions
 Database: organized collection of logically related data.
 Data: stored representations of meaningful objects and events
 Structured: numbers, text, dates
 Unstructured: images, video, documents
 Information: data processed to increase knowledge in the person using
the data.
 Metadata (data dictionary, system catalog): data that describes the
properties and context of user data.
Reviewed By Mr. Mahmoud Rafeek Alfarra
Descriptions of the properties or characteristics of the
data, including data types, field sizes, allowable
values, and data context
Reviewed By Mr. Mahmoud Rafeek Alfarra
Database Management System
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A software system that is used to create, maintain, and provide
controlled access to user databases
DBMS manages data resources like an operating system manages hardware resources
Reviewed By Mr. Mahmoud Rafeek Alfarra
Enterprise Data Model
Graphical model
showing high-level
entities and
relationships for the
organization
Reviewed By Mr. Mahmoud Rafeek Alfarra
One customer may place
many orders, but each
order is placed by a
single customer
 One-to-many
relationship
Reviewed By Mr. Mahmoud Rafeek Alfarra
One order has many order
lines; each order line is
associated with a single order
 One-to-many relationship
Reviewed By Mr. Mahmoud Rafeek Alfarra
One product can be in many
order lines, each order line
refers to a single product
 One-to-many relationship
Reviewed By Mr. Mahmoud Rafeek Alfarra
Therefore, one order involves
many products and one product
is involved in many orders
 Many-to-many relationship
Reviewed By Mr. Mahmoud Rafeek Alfarra
Reviewed By Mr. Mahmoud Rafeek Alfarra
Workgroup database with local area network
Reviewed By Mr. Mahmoud Rafeek Alfarra
An enterprise
data warehouse
Enterprise constraints:
additional rules specified by
the users or database
administrators of a database.
Reviewed By Mr. Mahmoud Rafeek Alfarra
Components of the Database Environment
 CASE Tools – computer-aided software engineering
 Repository – centralized storehouse of metadata
 Database Management System (DBMS) – software for managing the
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database
Database – storehouse of the data
Application Programs – software using the data
User Interface – text and graphical displays to users
Data Administrators – personnel responsible for maintaining the database
System Developers – personnel responsible for designing databases and
software
End Users – people who use the applications and databases
Reviewed By Mr. Mahmoud Rafeek Alfarra
Components of
the database
environment
Reviewed By Mr. Mahmoud Rafeek Alfarra
Evolution of DB Systems
 Flat files - 1960s - 1980s
 Hierarchical – 1970s - 1990s
 Network – 1970s - 1990s
 Relational – 1980s - present
 Object-oriented – 1990s - present
 Object-relational – 1990s - present
 Data warehousing – 1980s - present
 Web-enabled – 1990s - present
Reviewed By Mr. Mahmoud Rafeek Alfarra
Enterprise Data Model
 First step in database development
 Specifies scope and general content
 Overall picture of organizational data at high level of
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abstraction
Entity-relationship diagram
Descriptions of entity types
Relationships between entities
Business rules
Reviewed By Mr. Mahmoud Rafeek Alfarra
Segment from enterprise data model
Enterprise data model describes
the high-level entities in an
organization and the
relationship between these
entities
Reviewed By Mr. Mahmoud Rafeek Alfarra
Two Approaches to DB and IS Development
 SDLC
 System Development Life Cycle
 Detailed, well-planned development process
 Time-consuming, but comprehensive
 Long development cycle
 Prototyping
 Rapid application development (RAD)
 Define database during development of initial prototype
 Repeat implementation and maintenance activities with new prototype versions
Reviewed By Mr. Mahmoud Rafeek Alfarra
Systems Development Life Cycle
enterprise modeling
Project Identification
and Selection
conceptual data modeling
Project Initiation
and Planning
conceptual data modeling
Analysis
logical database design
System Development Life
Cycle (SDLC) is the overall
Logical Design
process of developing
physical database design
information systems through
a multi step process from
Physical Design
investigation of initial
requirements through
analysis, design,
Implementation
implementation and
maintenance. There are
database implementation
Maintenance
many different models and
methodologies, but each
generally consists of a series
database maintenance
of defined steps or stages.
Reviewed By Mr. Mahmoud Rafeek Alfarra
Packaged Data Models
 Model components that can be purchased, customized,
and assembled into full-scale data models
 Advantages
 Reduced development time
 Higher model quality and reliability
 Two types:
 Universal data models
 Industry-specific data models
Reviewed By Mr. Mahmoud Rafeek Alfarra
Database Schema
 Physical Schema (Physical structures)
The physical representation of the database on the computer, this level describes how the data is stored
in the DB
 Conceptual Schema (E-R models)
The community view of the database, this level describes what data is stored in the DB and the
relationship among the data.
 External Schema
The users’ view of the DB, this level describes that part of the database that is relevant to each user
 User Views
 Subsets of Conceptual Schema
 Can be determined from business-function/data entity matrices
 DBA determines schema for different user
Reviewed By Mr. Mahmoud Rafeek Alfarra
Different people
have different
views of the
database…these
are the external
schema
The internal
schema is the
underlying
design and
implementation
Reviewed By Mr. Mahmoud Rafeek Alfarra
Three-tiered client/server database architecture
Reviewed By Mr. Mahmoud Rafeek Alfarra
Reviewed By Mr. Mahmoud Rafeek Alfarra