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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