Unit 2 – Application & Implication Module 1 – Information Management.
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Transcript of Unit 2 – Application & Implication Module 1 – Information Management.
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Unit 2 – Application & Implication
Module 1 – Information Management
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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
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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.
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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.
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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
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The Hierarchy of Data
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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
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Data Entities, Attributes, and Keys
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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
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The Database Approach
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The Database Approach
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The Database Approach
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The Database Approach
Table 3.2: Disadvantages of the Database Approach
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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?
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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
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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
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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
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Manipulating Data
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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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