ITEC36 (Sir Noel) Flashcards
known facts that can be recorded and have an implicit meaning
Data
it is a processed data by a computer to become more useful
Information
it is a collection of related data
Database
it is a collection of programs which enables its users to access database, manipulate data, reporting and representaion of data
Database Management System
it is an organized collection of structured infromation, or data, typically stored electronically in a computer system
Database
it access different parts of data and formulate the result of a request presentation and visualization of data
Queries
that may read some data and “update” certain values or generate new data and store that in the database
Transactions
used to hide storage details and present the users with a conceptual view of the database
Data Model
refer to the data model constructs rather than data storage details
program
supports only one user at a time
Single User Database
supports multiple users at the same time
MultiUser Database
Database can be classified according to:
Number of Users
Database Location
Expected Type and Extent of Use
Data distributed across several different site
Distributed Database
database is located at a single site
Centralized Database
database is located within more than one site
Decentralized Database
stores data used for tactical or strategic decision
Data Warehouse
supports a companies day to day operations
Operational Database
are the ones who really use and take the benefits of the database
Database User
Users may be divided into:
Actors on the scene
Workers behind the scene
Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring effieciency of operations
Database Administrators
Responsible to define the content, the structure, the constraints, and functions
ot transactions against the database. They must communicate with the end users and understand their needs.
Database Designers
access database occasionally when needed
Casual
they use the data for queries, reports and some of them update the database content.
End Users
they make up a large section of the end user population
Naive
These include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities.
Sophisticated
Mostly maintain personal databases using ready-to-use packaged applications
Stand Alone
They understand the user requirements of naïve and sophisticated users and design applications including canned transactions to meet those requirements.
System Analysts
Implement the specifications developed by analysts and test and debug them before deployment.
Application Programmers
There is an increasing need for such people who can analyze vast amounts of business data and real-time data (“Big Data”) for better decision making related to planning, advertising, marketing etc.
Business Analysts
Design and implement DBMS packages in the form of modules and interfaces and test and debug them.
System Designers and Implementors
Design and implement software systems called tools for modeling and designing databases, performance monitoring, prototyping, test data generation, user interface creation, simulation etc. that facilitate building of applications and allow using database effectively.
Tool Developers
They manage the actual running and maintenance of the database system hardware and software environment.
Operators and Maintenance Personnel
5 Advantage of database
Data Independence
Data Consistency
Controlled Redundancy
Data Integrity
Data Security
Database structure may evolve as new
requirements are defined.
Flexibility to change data structures
Extremely important for on-line
transaction systems such as shopping,
airline, hotel, car reservations
Availability of current information
Wasteful overlap of resources
and personnel can be avoided
by consolidating data and
applications across departments.
Economies of scale
were introduced in
late 1980s and early 1990s to
cater to the need of complex
data processing in CAD and
other applications.
Object-Oriented Database Management Systems
(OODBMSs)
was originally
introduced in 1970, was heavily
researched and experimented
within IBM Research and several
universities.
Relational model
contains data in HTML
(Hypertext markup language)
with links among pages
Web
A single unit of logic or
work, sometimes made up of multiple operations.
Transaction
is a major
part of database applications; allows hundreds of
concurrent transactions to execute per second.
OLTP (Online Transaction Processing)
Those who actually use
and control the database content, and those who
design, develop and maintain database applications
“Actors on the Scene”
Those who
design and develop the DBMS software and related
tools, and the computer systems operators
“Workers Behind the Scene”
is a vital concept in
a database. Only users authorized must be
allowed to access the database and their
identity must be authenticated using
username and password. Unauthorized users
shouldn’t be allowed to access the database
under any circumstances as its violets the
integrity constraints
Data Security
is defined as the storing of the
same data in multiple locations.
Data redundancy
is the process of organizing data
in a database. This includes creating tables and
establishing relationships between those tables
according to rules designed both to protect the
data and to make the database more flexible by
eliminating redundancy and inconsistent
dependency.
Normalization
Providing storage structures for
efficient query processing
indexes
is the module responsible for
executing database queries.
query processor
is the process of selecting an
efficient execution plan for evaluating the query.
Query optimization
describe the process of
creating and storing copies of data that can be
used to protect organizations against data loss.
Backup and recovery
refers to an interactive
system that provides access to information and
services using different computing platforms.
Multiple-User Interface (MUI)
refers to the correctness and
completeness of data within a database.
Data integrity
is defined as a property of DBMS that helps
you to change the Database schema at one
level of a database system without requiring
to change the schema at the next higher level.
Data Independence
in database
systems refers to the requirement that any
given database transaction must change
affected data only in allowed ways.
Data Consistency
occurs in database systems which have a field
that is repeated in two or more tables. …
Database normalization prevents redundancy
and makes the best possible usage of
storage.)
Controlled Redundancy
is the
oldest type of the data model. It
was developed by IBM in 1968. It organizes data in the tree-like
structure
Hierarchical data model
It is the
advance version of the hierarchical
data model. To organize data it uses
directed graphs instead of the treestructure.
Network Data Model
is
a database management system that
supports the creation and modeling of
data as objects.
object-oriented database
management system
it is referred to as parent table.
Table
it is referred to as child table.
Related Table
indicates that there can be only one
matching record in that table
Number 1
indicates that many records can
include the same ID; may appear more than
once
The ∞ symbol
When each item in each table only appears
at once.
One-To-One (1-1)
When one item in one table can have a
relationship to multiple items in another
table.
One-To-Many (1-∞)
When one or more items in one table can
have a relationship to one or more items in
another table.
Many-To-Many (∞-∞)
To prevent invalid data and to keep
references in sync across table relationship
Enforce Referential Integrity
To make sure that data in related Fields is
updated in all related Tables.
Cascade Update Related Fields
The decision to select this depends on
whether you need to retain records in some
tables even though they right be deleted
from other tables.
It is optionally checked in MS Access
Cascade Delete Related Records
supports a small
number / a small group of users
Workgroup Database
supports a large
number / large number of users (more
than one building, multiple buildings,
wide area network) 2 or more system
Enterprise Database
