RELATIONAL DATABASE
FUNDAMENTALS
Information is everywhere in an
organization
Information is stored in databases
·
Database – maintains information about various
types of objects (inventory), events (transactions), people (employees), and
places (warehouses)
Database
models include:
·
Hierarchical database model – information is organized into a
tree-like structure (using parent/child relationships) in such a way that it
cannot have too many relationships
·
Network database model – a flexible way of representing objects
and their relationships
·
Relational database model – stores information in the form of
logically related two-dimensional tables
Entities and Attributes
Entity – a
person, place, thing, transaction, or event about which information is stored
Attributes (fields, columns) – characteristics or properties of an entity class
Keys and Relationships
Primary key – a
field (or group of fields) that uniquely identifies a given entity in a table
Foreign key – a
primary key of one table that appears an attribute in another table and acts to
provide a logical relationship among the two tables
RELATIONAL DATABASE
ADVANTAGES
Database advantages from a business perspective
include
·
Increased flexibility
·
Increased scalability and performance
·
Reduced information redundancy
·
Increased information integrity (quality)
·
Increased information security
Increased Flexibility
A well-designed database should:
•
Handle
changes quickly and easily
•
Provide
users with different views
•
Have
only one physical view
Physical
view – deals
with the physical storage of information on a storage device
•
Have
multiple logical views
Logical
view – focuses on how users logically
access information
Increased Scalability and Performance
A database must scale to meet increased
demand, while maintaining acceptable
performance levels
•
Scalability – refers to how well a system can
adapt to increased demands
•
Performance – measures how quickly a system
performs a certain process or transaction
Reduced Information Redundancy
•
One of the primary
goals of a database is to eliminate information redundancy by recording each
piece of information in only one place
•
Databases reduce
information redundancy
Redundancy – the duplication of information or storing the same information in
multiple places
•
Inconsistency is one
of the primary problems with redundant information
Increase Information Integrity (Quality)
•
Information integrity –
measures the quality of information
•
Integrity constraint –
rules that help ensure the quality of information
Increased Information Security
•
Information is an organizational asset and must be
protected
•
Databases offer several security features including:
Password – provides authentication of the user
Access level – determines who has access to the different
types of information
Access control – determines types of user access, such as
read-only access
DATABASE MANAGEMENT
SYSTEMS
software through which users and application
programs interact with a database
DATA-DRIVEN WEB SITES
A data-driven Web site is an interactive Web
site kept constantly updated and relevant to the needs of its customers through
the use of a database. Data-driven Web sites are especially useful when the
site offers a great deal of information, products, or services. Web site
visitors are frequently angered if they are buried under an avalanche of information
when searching a Web site. A data-driven Web site invites visitors to select
and view what they are interested in by inserting a query, which the Web site
then analyzes and custom builds a Web page in real-time that satisfies the
query. The figure displays a Wikipedia user querying business intelligence and
the database sending back the appropriate Web page that satisfies the user’s
request.
Data-Driven Web Site
Business Advantages
•
Development: Allows the Web site owner to make
changes any time—all without having to rely on a developer or knowing HTML
programming. A well-structured, data-driven Web site enables updating with
little or no training.
•
Content
management: A static Web site requires a
programmer to make updates. This adds an unnecessary layer between the business
and its Web content, which can lead to misunderstandings and slow turnarounds
for desired changes.
•
Future
expandability: Having a data-driven Web site enables the site to grow faster than would
be possible with a static site. Changing
the layout, displays, and functionality of the site (adding more features and
sections) is easier with a data-driven solution.
•
Minimizing
human error: Even the most competent programmer charged with the task of maintaining
many pages will overlook things and make mistakes. This will lead to bugs and
inconsistencies that can be time consuming and expensive to track down and fix.
Unfortunately, users who come across these bugs will likely become irritated
and may leave the site. A well-designed, data-driven Web site will have ”error
trapping” mechanisms to ensure that required information is filled out
correctly and that content is entered and displayed in its correct format.
•
Cutting
production and update costs: A data-driven Web site can be updated and ”published” by any competent
data entry or administrative person. In addition to being convenient and more
affordable, changes and updates will take a fraction of the time that they
would with a static site. While training a competent programmer can take months
or even years, training a data entry person can be done in 30 to 60 minutes.
•
More
efficient: By their very nature, computers are
excellent at keeping volumes of information intact. With a data-driven
solution, the system keeps track of the templates, so users do not have to.
Global changes to layout, navigation, or site structure would need to be
programmed only once, in one place, and the site itself will take care of
propagating those changes to the appropriate pages and areas. A data-driven infrastructure
will improve the reliability and stability of a Web site, while greatly
reducing the chance of ”breaking” some part of the site when adding new areas.
•
Improved
Stability: Any programmer who has to update a Web site from ”static” templates must
be very organized to keep track of all the source files. If a programmer leaves
unexpectedly, it could involve re-creating existing work if those source files
cannot be found. Plus, if there were any changes to the templates, the new
programmer must be careful to use only the latest version. With a data-driven
Web site, there is peace of mind, knowing the content is never lost—even if
your programmer is.
Integrating
Information among Multiple Databases
•
Integration – allows
separate systems to communicate directly with each other
Forward
integration – takes information
entered into a given system and sends it automatically to all downstream
systems and processes
Backward
integration – takes information
entered into a given system and sends it automatically to all upstream systems
and processes
•
One of the
biggest benefits of integration is that organizations only have to enter
information into the systems once and it is automatically sent to all of the
other systems throughout the organization
•
This
feature alone creates huge advantages for organizations because it reduces
information redundancy and ensures accuracy and completeness
•
Without
integrations an organization would have to enter information into every single
system that requires the information from marketing and sales to billing and
customer service
Integrating
Information among Multiple Databases
Building a
central repository specifically for integrated information
•
The above
figure displays an example of customer information integrated using this method
•
Users can
create, read, update, and delete in the main customer repository, and it is
automatically sent to all of the other databases
•
This
method does not follow the business process when building the integrations
•
Business-critical
integrity constraints still need to be built to ensure information is only ever
entered into the customer repository, otherwise the information will become
out-of-sync
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