Unit 2 – Application & Implication

Module 1 – Information Management

DifferentiateDifferentiate between thesethese Terms used in Information Management

Fields – a field is a unit of data consisting of one or

more character ex Name, Tel#, Address

Records – a collection of related fields ex Name, ID,

Address

Tables – a number of related records

Relation – a 2-dimentional table containing rows and

columns of data

Tuple – a column in a relation

Attribute – a row in a relation

Null values - the value given an attribute in a tuple –

if the attribute is inapplicable or its value is unknown

DifferentiateDifferentiate between thesethese Terms used in Information Management

Files – a file is collection of related records

ex. Data on all students of 6th form IT class

Database – an integrated collection files

Database Management System – system

software that facilitate the management of a

database

Relational Database Schema – A listing

showing relation names, attribute names, key

attributes and foreign keys.

DifferentiateDifferentiate between thesethese Terms used in Information Management

Key – a minimal set of attributes that uniquely identifies each row in a relation

Superkey- A set of attributes that uniquely identifies each row in a relation.

Composite key- a key consisting of more than one attribute.

Candidate Key- Any set of attributes that could be chosen as a key of a relation.

Primary Key – The candidate key designated for principal use in uniquely identifying rows

in a relation. Foreign Key- A set of attributes in one relation

that constitutes a key in some other (or possibly the same) relation; used to indicate logical links between relations.

The Hierarchy of Data Bit (a binary digit): a

circuit that is either on or off

Byte: eight bits Character: basic

building block of informationEach byte

represents a character

Can be an uppercase letter, lowercase letter, numeric digit, or special symbol

Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity

Record: a collection of related data fields

File: a collection of related records

Database: a collection of integrated and related files

Hierarchy of data: bits, characters, fields, records, files, and databases

The Hierarchy of Data

Data Entities, Attributes, and KeysEntity: a generalized class of people, places, or

things (objects) for which data is collected, stored, and maintained

Attribute: characteristic of an entityData item: value of an attribute

Key: field or set of fields in a record that is used to identify the record

Primary key: field or set of fields that uniquely identifies the record

Data Entities, Attributes, and Keys

The Database ApproachTraditional approach to database management:

separate data files are created for each application

Results in data redundancy (duplication)

Data redundancy conflicts with data integrity

Database approach to database management: pool of related data is shared by multiple applications

Significant advantages over traditional approach

The Database Approach

The Database Approach

The Database Approach

The Database Approach

Table 3.2: Disadvantages of the Database Approach

Data Modeling and the Relational Database Model

When building a database, consider:

Content: What data should be collected, at what cost?

Access: What data should be provided to which users and when?

Logical structure: How should data be arranged to make sense to a given user?

Physical organization: Where should data be physically located?

Data Modeling

Building a database requires two types of designsLogical design

Abstract model of how data should be structured and arranged to meet an organization’s information needs

Physical designFine-tunes the logical database design for

performance and cost considerations

Data Modeling

Data model: a diagram of data entities and their relationships

Entity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data

The Relational Database Model Relational model: all

data elements are placed in two-dimensional tables (relations), which are the logical equivalent of files

In the relational model Each row of a table

represents a data entity

Columns of the table represent attributes

Domain: the allowable values for data attributes

Manipulating Data

Database Management Systems (DBsMS)

Interface between:Database and application programs Database and the user

Creating and implementing the right database system ensures that the database will support both business activities and goals

DBMS: a group of programs used as an interface between a database and application programs or a database and the user

Overview of Database Types Flat file: A flat file database is a database which,

when not being used, is stored on its host computer system as an ordinary, non-indexed "flat" file. To access the structure of the data and manipulate it, the file must be read in its entirety into the computer's memory.

Single user : Only one person can use the database at a timeExamples: Access, FileMaker & InfoPath

Multiple user:Allows dozens or hundreds of people to access

the same database system at the same timeExamples: Oracle, Sybase, and IBM

Creating and Modifying the Database

Data definition language (DDL)

Collection of instructions/commands that define & describe data and data relationships in a database(db)

Allows db creator to describe the data & the data relationships that are to be contained in the schema

Data dictionary: a detailed description of all the data used in the database

Storing and Retrieving Data When an application

requests data from the DBMS, the application follows a logical access path

When the DBMS goes to a storage device to retrieve the requested data, it follows a path to the physical location (physical access path) where the data is stored

Manipulating Data & Generating Reports

Query-By-Example (QBE): a visual approach to developing database queries or requests

Data manipulation language (DML): commands that manipulate the data in a database

Structured Query Language (SQL): ANSI standard query language for relational databases

Database programs can produce reports, documents, and other outputs

Database AdministrationDatabase administrator (DBA): directs or

performs all activities to maintain a database environment

Designing, implementing, and maintaining the database system and the DBMS

Establishing policies and procedures

Employee training

Popular Database Management Systems

Popular DBMSs for end users: Microsoft Access and FileMaker Pro

Entire market includes databases by IBM, Oracle, and Microsoft

Examples of open-source database systems: PostgreSQL and MySQL

Many traditional database programs are now available on open-source operating systems

Selecting a DBMSImportant characteristics of databases to

consider

Size of the databaseCost of the systemNumber of concurrent usersPerformanceAbility to be integrated with other systemsVendor considerations

Using Databases with Other Software

Database management systems are often used with other software packages or the Internet

A database management system can act as a front-end application or a back-end application

Front-end application: interacts with users Back-end application: interacts with

applications

Linking Databases to the InternetLinking databases to the Internet is important

for many organizations and people

Semantic Web

Developing a seamless integration of traditional databases with the Internet

Allows people to access and manipulate a number of traditional databases at the same time through the Internet

Business Intelligence

Business intelligence (BI): gathering the right information in a timely manner and usable form and analyzing it to have a positive impact on businessTurns data into useful

information that is then distributed throughout an enterprise

Competitive intelligence: aspect of business intelligence limited to information about competitors and the ways that knowledge affects strategy, tactics, and operations

Counterintelligence: steps an organization takes to protect information sought by “hostile” intelligence gatherers

Distributed Databases

Distributed databaseData may be spread across several

smaller databases connected via telecommunications devices

Corporations get more flexibility in how databases are organized and used

Replicated databaseHolds a duplicate set of frequently used

data

Object-Oriented and Object-Relational Database Management Systems

Object-oriented databaseStores both data and its processing instructions

Method: a procedure or actionMessage: a request to execute or run a method

Visual, Audio, and Other Database Systems

Visual databases for storing imagesAudio databases for storing soundVirtual database systems: allow different

databases to work together as a unified database system

Other special-purpose database systemsSpatial data technology: stores and

accesses data according to the locations it describes and permits spatial queries and analysis

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