Databases and Database Users

databases

n A Database: is a collection of related data.
n Database properties:
Ø It represents some aspect of the real world
[miniworld or Universe of Discourse (UoD)]
Ø It is a logically coherent collection of data with inherent meaning
Ø It is designed, built and populated with data for specific purpose

*** Some other properties :


n A Database can be of any size ranging from few number of records have hundreds or thousands bytes to gigabytes or terabytes
n A Database may be generated and managed manually or it may be computerized
n The computerized choice may be by a group of application programs implemented specifically for that application or by a:
Database Management System (DBMS)

Advantages of Using DBMS

* Controlling Redundancy
* Restricting Unauthorized Access
* Providing Persistent Storage
* Permitting Inferencing
* Providing Multiple User Interfaces
* Presenting Complex Relationship
* Enforcing Integrity Constraints
* Providing Backup and Recovery
People indirectly involved in DB
These people are not interested in the DB itself but they are providing the necessary environment for the DB users.
* DBMS system designers and implementers
The persons who design and implement the DBMS modules.
* Tool Developers
The persons who design the tools which enables DB users in design and use their DB
* Operators and Maintenance personnel
The persons responsible for running and marinating the software and hardware environment for the DB system.

about DBMS

DBMS is: a collection of programs that enables users to create and maintain a database
n It is a general-purpose software system enables us in Defining, Constructing and Manipulating DB:
Ø Defining: specifying the data types, structures and constraints
Ø Constructing: storing the data in the DB
Ø Manipulating: as querying, updating and generating reports
Database + DBMS ................. Database System

Example

Example
n University database: to maintain students, courses and grades.
n We may have five files:
Ø STUDENT
Ø COURSE
Ø SECTION
Ø PREREQUISITE
Ø GRADE_REPORT

the Advantages of Using DBMS

Advantages of Using DBMS

Advantages of Using DBMS
n Controlling Redundancy
n Restricting Unauthorized Access
n Providing Persistent Storage
n Permitting Inferencing
n Providing Multiple User Interfaces
n Presenting Complex Relationship
n Enforcing Integrity Constraints
n Providing Backup and Recovery

Some other benefits
n Enforcing Standards
n Reduced Application development time
n Flexibility
n Up-to-date Information
n Economies of Scale

When Not to Use a DBMS
n Unnecessary overhead costs
(high initial cost – Generality – overhead of capabilities)
n Database and applications are simple
n Stringent real-time requirements
n Multiple-user access is not required
Some Previous I talked about

n Database Administrator (DBA)
DBA administrates DB, DBMS, applications, user accessing authorization, monitoring and tuning.
n Database Designers
DB designers identify the data to be stored and its structure to efficiently fulfill all users requirements.
n End Users
Ø Casual end users:Occasionally access DB using sophisticated query language (Managers)
Ø Naive end users: Querying and updating DB using canned transactions (bank tellers, etc..)
Ø Sophisticated end users: familiar with DBMS capabilities and using it to implement their complex requirements (engineers, scientists, analysts, etc. )
Ø Stand-alone users: using ready-made packages and tools to handle their personal DB.
n System Analysts and Application Programmers
Analysts determine the users requirements and develop the appropriate transaction specifications.
Application programmers implement these requirements to programs.
Analysts + Programmers are called SOFTWARE ENGINEERS

Database Characteristics

These characteristics distinguish DB from File-processing approach:
n Self-Describing Nature of DB
Catalog to hold description(Data + Meta-data to describe the DB)
n Insulation between Programs and Data
program-data independence , program-operation independence
Data abstraction
n Support Multiple Views of Data
Multiple derived views – Virtual views
n Sharing Data and Multiuser Transaction Processing
Concurrency control for OLTP (On-Line Transaction Processing
those are the major properties for the databases from my opinion

People involved in DB

n Database Administrator (DBA)
DBA administrates DB, DBMS, applications, user accessing authorization, monitoring and tuning.
n Database Designers
DB designers identify the data to be stored and its structure to efficiently fulfill all users requirements.
n End Users
Ø Casual end users:Occasionally access DB using sophisticated query language (Managers)
Ø Naive end users: Querying and updating DB using canned transactions (bank tellers, etc..)
Ø Sophisticated end users: familiar with DBMS capabilities and using it to implement their complex requirements (engineers, scientists, analysts, etc. )
Ø Stand-alone users: using ready-made packages and tools to handle their personal DB.
n System Analysts and Application Programmers
Analysts determine the users requirements and develop the appropriate transaction specifications.
Application programmers implement these requirements to programs.
Analysts + Programmers are called SOFTWARE ENGINEERS

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