Transcript Slides

CSI315
Web Development Technologies
Continued
Data
• Data is an un-processed collection or
representation of raw facts, concepts, or
instructions in a manner suitable for
communication, interpretation, or processing by
humans or by automatic means. It can be
defined as unprocessed information.
• Data that has been interpreted, translated, or
transformed to reveal the underlying meaning is
called information. Information is the result of
processing, manipulating and organizing data in
a way that adds to the knowledge of the
person receiving
•
Data is converted into information, and
information is converted into knowledge.
The Data Layer
• All of the web technologies at the Data
Layer define, describe, or standardize one
or more of the data characteristics:
– Data types (letters, numbers, dates, ints,
floats. strings )
– Data descriptions (reference keywords)
– Data formats (DD/MM/YYYY, $ )
– Data values
Data is stored in databases across the
Internet
The Database
• A logical collection of interrelated data
organized to meet the needs and
structure of an organization.
• A collection of information organized
and presented to serve a specific
purpose. A computerized database is an
updated, organized file of machine
readable information that is rapidly
searched and retrieved by computer.
• A collection of related electronic
records in a standardized format,
searchable in a variety of ways, such as
title, author, subject, and keyword.
Databases
• Databases are designed to offer an
organized mechanism for storing, managing
and retrieving information.
• Data from the database extracted from
the internal (Finance, Marketing,
Production, Personnel etc.) and external
sources like industry data, regional
employment data etc.
• Data may organized in one or more
separate databases or in a data
warehouse, or a special independent
database.
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Database Actions
Actions that you can perform to a
database
• Retrieve all records that match
certain criteria
• Update records in bulk
• Cross-reference records in different
tables
• Perform complex aggregate
calculations
Database Management System
(DBMS)
A collection of computer programs that allow
creation, storage, modification, and
extraction of information from the
database.
• Captures data for inclusion in the database
• Updates(adds, deletes, edits, changes) data records and
files
• Interrelates data from different sources
• Retrieves data from the database for queries and reports
• Provides comprehensive data security-access, recovery
• Performs complex data manipulation tasks based on queries
• Tracks data within the DSS
• Manages data through a data dictionary
The Query Facility
Performs queries on the data
• It accepts data from other DSS
components
• Determines how the request can be
filled ( consults data dictionary)
• Formulates the detailed request
• Returns the results to the issuer of
request
Data Directory
• A catalog of of all data in the
database
• Contains data item definitions, their
sources and exact meaning
• Supports updates like additions and
deletions
Web Databases(OLAP)
• Analytic databases (a.k.a. OLAP- On Line
Analytical Processing) are primarily static,
read-only databases which store archived,
historical data used for analysis .
• They enable analysts, managers and
executives to gain insight into data
through fast, consistent, interactive
access. For example a user could
– request spreadsheet analysis showing all of
a company's products sold in a certain
month
– compare revenue figures with those for the
same products another month
– see a comparison of other product sales in
another branch/company in the same time
period
Web Databases (OLTP)
• Operational databases (a.k.a. OLTP On Line
Transaction Processing
• Databases that allow the real-time
processing of SQL transactions to support
e-commerce and other time-critical
applications. This type of processing is
known as online transaction processing
(OLTP )
• An OLTP database has Read and Write
access. This is where transactions are
actually entered, modified, and/or deleted.
Data model
• A data model is a "description" of both a
container for data and a methodology for
storing and retrieving data from that
container.
• Data models are abstractions, often at
times mathematical algorithms and
concepts
• Used for presenting entities of interest
and their relationships in the database
Database Models
Relational Database :
• most popular form. Table = data file
• Data collected in 2-dimensional tabular form.
Columns(field) e.g Data field called Cu. Name ,ID,
Address etc. ), rows (records made up of several
field)
• Data files may be related by a common field
forming a relation.
Hierarchical Databases
Data items arranged in a top down
fashion
• Logical links between data items e.g
Database Models Cntd.
Networked Databases
• Structure allows dependencies among elements
• Saves storage space through sharing of data items
Database Models Cntd
O-O Databases
• Defines data as objects and models natural
relationships between objects(inheritance,
encapsulation, behavior etc.)
• Uses a hierarchy of classes and sub-subclasses
Multimedia based databases
Uses a variety of formats in addition to text and
numeric fields (bitmaps,video clips, sound, virtual
reality)
Database Connectivity
two ways
• connecting to the database directly
using a command shell
• connecting to the database over the
network using sockets (if that
database allows such interaction).
Database Issues:
Online Database: A collection of information
organized in such a way that a website visitor can
quickly select desired pieces of data.
Uses include:
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Show visitors your vast inventory by price,
category and pictures.
Let customers use a search function to
quickly find a product or service.
A must for e-commerce websites that carry
10 or more items.
Quickly change and update your website
through the administration tool of the
website.
Store information.
Database Issues
(Tutorial)
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Data warehousing
Data mining