Stid1103 Ch10 Database

CHAPTER TEN (10)CHAPTER TEN (10)

INTRODUCTION TO DATABASE

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Learning ObjectivesLearning Objectives

After completing this chapter you will be able to:- Introduce the basic concepts of database. Explain database system model. Describe Evolution of database. Explain basic operation in build database systems. Describe the use of table, relationship, query, form

and report.

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Chapter OutlineChapter Outline Introduction Creating the database Database Terms Hierarchy of Data Database approach Database Model Tutorial: Microsoft Access

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IntroductionIntroduction

A database consists of an organized collection of data for one or more uses, typically in digital form.

Digital databases are managed using database management systems, which store database contents, allowing data creation and maintenance, and search and other access.

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DataData

Data are raw facts.Raw data refers to a collection of

numbers, characters, images or other outputs from devices that collect information to convert physical quantities into symbols, that are unprocessed.

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InformationInformation

Information is data that is organizedand meaningful.

Data is typically further processed by a human or input into a computer, stored and processed there, or transmitted (output) to another human or computer in the form on information.

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Data and InformationData and Information

Computers process data into information.

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Step 1. The data, including a photograph, is entered and stored on the hard disk.

Step 2. The computer extracts the data from disk.

Step 3. The receipt is created and printed.

data stored on disk processing

receipt

DatabaseDatabase

Collection of data organized so you can access, retrieve, and use it.

Database software also called database management system (DBMS).

Database software allows you to– Create database– Add, change, and delete data– Sort and retrieve data– Create forms and reports

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Creating the DatabaseCreating the Database

To create a database, designers must develop a conceptual design and a physical design.

Conceptual design: An abstract model of a database from the user or business perspective.

Physical design: Layout that shows how a database is actually arranged on storage devices.

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Conceptual Data ModelConceptual Data Model

A map of concepts and their relationships. It describes the things of significance to an

organization (entity classes), about which it is inclined/influence to collect information, and characteristics of (attributes) and associations between pairs of those things of significance (relationships).

Example: Entity-relationship modeling

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Database TermsDatabase Terms

Entity-relationship modeling: The process of designing a database by organizing data entities to be used and identifying the relationships among them.

Entity-relationship (ER) diagram: Document that shows data entities and attributes and relationships among them.

Entity classes: A grouping of entities of a given type.

Instance: A particular entity within an entity class.04/11/23 11STID 1103

Database Terms (cont…)Database Terms (cont…)

Identifier: An attribute that identifies an entity instance.

Relationships: The conceptual linking of entities in a database.

The number of entities in a relationship is the degree of the relationship. Relationships between two items are common and are called binary relationships.

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Binary RelationshipsBinary Relationships

There are three types of binary relationships: – 1:1 (one-to-one) relationship: a single-entity instance of

one type is related to a single-entity instance of another type.

– 1: M (one-to-many) relationship: a single-entity instance of one type is related to many-entity instance of another type.

– M:M (many-to-many) relationship: a single-entity instance of one type is related to many-entity of another type and vice versa.

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Entity- relationship diagram Entity- relationship diagram modelmodel

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Normalization ~ A method for analyzing and reducing a relational database to its most streamlined form for minimum redundancy, maximum data integrity, and best processing performance

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Normalized relationNormalized relation

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Non-normalized relationNon-normalized relation

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Physical view: The plan for the actual, physical arrangement and location of data in the direct access storage devices (DASDs) of a database management system.

Logical view: The user’s view of the data and the software programs that process that data in a database management system.

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The Hierarchy of DataThe Hierarchy of Data

Refers to the systematic organization of data, often in a hierarchical form.

A hierarchy is an arrangement of items (objects, names, values, categories, etc.) in which the items are represented as being "above," "below," or "at the same level as" one another. (the items are represented as being "above," "below," or "at the same level as" one another)

Database contains files, file contains records, record contains fields, field contains characters.

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The Hierarchy of DataThe Hierarchy of Data

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Database contains files, file contains records, record contains fields, field contains characters, characters are represented by bytes and bits.

FieldField

A data field holds a single fact. Combination of one or more characters. Example: “October 18, 2010". This can

be treated as a single date field (eg birthdate), or 3 fields, namely, month, day of month and year.

Smallest unit of data user accesses– Field size defines the maximum number of

characters a field can contain– Field name uniquely identifies each field– Data type specifies kind of data field contains

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Data TypeData Type A classification identifying one of various types of

data– Text (also called alphanumeric) — letters, numbers, or

special characters– Numeric - numbers only– AutoNumber - unique number automatically assigned to

each new record– Currency - dollar and cent amounts or numbers

containing decimal values– Date - month, day, year, and sometimes time– Memo - lengthy text entries

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Data Type (cont…)Data Type (cont…)

Yes/No (also called Boolean) — only the values Yes or No (or True or False)

Hyperlink - Web address that links to document or Web page

Object - OLE Object (Object Linking and Embedding) or BLOB (Binary Large Object) - photograph, audio, video, or document created in other application such as word processing or spreadsheet (OLE object ~

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RecordRecord

A record (tuple) is a collection of related fields or a group of related fields.

An Employee record may contain a name field(s), address fields, birthdate field and so on.

Key field, or primary key is a field or combination of fields that uniquely identifies each record in the table.

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FileFile

A file is a collection of related records. If there are 100 employees, then each

employee would have a record (e.g. called Employee Personal Details record) and the collection of 100 such records would constitute a file (in this case, called Employee Personal Details file).

Files are integrated into a database. This is done using a Database Management System.

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Data FileData File

Collection of related records stored on disk

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key field

records fields

22 Fifth Avenue

P.O. Box 45

15 Duluth Street

33099 Clark Street

1029 Wolf Avenue

Address

Auburn

Clanton

Prattville

Montgomery

Montgomery

City

ALWeinbergJonah3928

ALMarcus4872

ALValesquezAdrian3376

ALMurrayShannon2928

ALVandenbergDonna2295

StateLast NameFirst NameMember ID

Green

File Processing SystemFile Processing System

Each department or area within organization has own set of files.

Records in one file may not relate to records in any other file.

May have weaknesses– Data redundancy—same fields stored in multiple

files– Isolated data—data stored in separate files so it is

difficult to access

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Database ApproachDatabase Approach

Many programs and users can share data in database.

Secures data so only authorized users can access certain data

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Database Approach (cont…)Database Approach (cont…)

Strengths of the database approach– Reduced data redundancy– Improved data integrity/consistency– Shared data– Easier access– Reduced development time

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File Processing Versus DatabasesFile Processing Versus Databases

How do a database application and a file processing application differ in the way they store data?

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Example of Database Example of Database Management System (DBMS)Management System (DBMS)

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Personal computer, midrange server, mainframe

IBM CorporationDB2


IBM CorporationInformix

ServerMicrosoft CorporationSQL Server

Personal computer, midrange server, PDA

Sybase Inc.Sybase

Personal computer, midrange server, mainframe, PDA

Oracle CorporationOracle


Computer Associates International, Inc.

Ingres

Personal computer, server, PDAMicrosoft CorporationAccess

Computer TypeManufacturerDatabase

DBMS TermsDBMS Terms

Data dictionary Structured Query Language (SQL) Query Query by Example (QBE) Form Report generator Data model

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Data DictionaryData Dictionary Known as metadata

repository, a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format.

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Contains data about each file in database and each field within those files.

Structured Query Language Structured Query Language (SQL)(SQL) A database computer language designed for

managing data in relational database management systems (RDBMS).

Allows you to manage, update, and retrieve data Has special keywords and rules included in SQL

statements

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SQL statementSQL statement results

QueryQuery

Request for specific data from a database.

Query language consists of simple, English-like statements that allow users to specify data to display, print, or store.

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Step 1. Select the fields you want to display in the resulting query.

Step 2. Assign a name to the query, so you can open it later.

Step 3. View query on the screen.

Query by Example (QBE)Query by Example (QBE) A database query language for relational databases Program retrieves records that match criteria entered in form fields Has a graphical user interface that assists users with retrieving

data

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Query by example screen

criteria

Query results

FormForm Window on screen that

provides areas for entering or changing data in database.

Used to retrieve and maintain data in a database.

Form that sends data across network or Internet is called e-form, short for electronic form.

Report GeneratorReport Generator

Also called report writer. Allows user to design a report on screen, retrieve

data into report design, then display or print reports.

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Data ModelData Model

Rules and standards that define how database organizes data and how users view organization of data.

The three most common data models are hierarchical, network, and relational.

Other types of data models include multidimensional, object-relational, hypermedia, embedded, and virtual.

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Relational Database ModelRelational Database Model

Stores data in tables that consist of rows and columns– Each row has primary key– Each column has unique name

Stores data relationships. Uses specialized terminology:

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RelationshipRelationship

Connection within data; link tables sharing the common field.

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Hierarchical Database ModelHierarchical Database Model Structures data into an inverted “tree” in which each

record contains two elements, a single root or master field, often called a key, and a variable number of subordinate fields.

Advantage is the speed and efficiency with which it can be searched for data.

problems: – Access to data in this model is predefined by the database

administrator before the programs that access the data are written.

– Programmers must follow the hierarchy established by the data structure.

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Hierarchical Database ModelHierarchical Database Model

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Network Database ModelNetwork Database Model

Data model that creates relationships among data in which subordinate records can be linked to more than one data element.

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Example of Database ModelExample of Database Model

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Advantages and Disadvantages Advantages and Disadvantages of Logical Data Modelsof Logical Data Models

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Model Advantages Disadvantages

Hierarchical database

Searching is fast and efficient. Access to data is predefined by exclusively hierarchical relationships, predetermined by

administrator. Limited search/query

flexibility. Not all data are naturally

hierarchical.

Network Many more relationships can be defined. There is greater speed and efficiency than with relational database models.

This is the most complicated database model to design, Implement, and maintain. Greater query flexibility than with hierarchical model, but less than with relational model.

Relational database Conceptual simplicity; there are no predefined relationships among data. High flexibility in ad-hoc querying. New data and records can be added easily.

Processing efficiency and speed are lower. Data redundancy is common, requiring additional maintenance.

Emerging Database ModelEmerging Database Model Two emerging data models are the object-

relational and hypermedia models– Object-relational database model: Data model that

adds new object storage capabilities to relational databases.

– Hypermedia database model: Data model that stores chunks of information in nodes that can contain data in a variety of media; users can branch to related data in any kind of relationship.

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Specialized Database ModelSpecialized Database Model Geographical information database: Data

model that contains locational data for overlaying on maps or images.

Knowledge database: Data model that can store decision rules that can be used for expert decision making.

Small-footprint database: The subset of a larger database provided for field workers.

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Specialized Database Model Specialized Database Model (cont…)(cont…)

Embedded database: A database built into devices or into applications; designed to be self-sufficient and to require little or no administration.

Virtual database: A database that consists only of software; manages data that can physically reside anywhere on the network and in a variety of formats.

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Object-Oriented Database Object-Oriented Database (OODB)(OODB)

a database model in which information is represented in the form of objects.

Object is item that contains data, as well as actions that read or process data.

Often uses object query language (OQL).Advantages:

– Can store more types of data.– Can access data faster

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Examples of applications for an Examples of applications for an object-oriented database?object-oriented database?

Multimedia databases– Store images, audio clips, and/or video clips

Hypertext databases– Contain text links

to other documents

Hypermedia databases– Contain text, graphics, video, and sound

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Examples of applications for an Examples of applications for an object-oriented database?object-oriented database?

Computer-aided design (CAD) databases– Store data about engineering, architectural, and

scientific designs Groupware databases– Store documents such as schedules, calendars,

manuals, memos, and reports

Web databases– Link to e-form on Web page

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TUTORIALTUTORIAL

MICROSOFT ACCESS 2007

http://www.gcflearnfree.org/computer/topic.aspx?id=146

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Stid1103 Ch10 Database

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