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Lesson 6

Chapter 5

Database Management

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Portfolio and Ecommerce Portfolio and Ecommerce HTML AssignmentHTML Assignment

Assignment is on course web space at http://www.courses.psu.edu/infsy/infsy540/rak13/HTML_Portfolio.html

Part of the assignment is to do research on ecommerce.

The first version of your portfolio.html page and subsequent sections of your site must be posted by the October 31st class. The final site must be online by November 28. – There are individual and team activities that need to take

place between these times.

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Case 2: Cisco Systems ArchitectureCase 2: Cisco Systems Architecture

What’s this case about?When did Cisco go public?What does Cisco stand for?What is Cisco’s mission?

IT Interaction Modelhttp://equity.stern.nyu.edu/~msilver/mbacore/itimhdo.htm

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Learning ObjectivesLearning Objectives

Know the difference between a database and a spreadsheet.

Identify the objects available in a relational database and their purpose.

Know the difference between a query and a filter.

Identify typical problems that occur with MS Access and other “personal” vice “enterprise” databases.

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Shared DataShared Data

Poorly organized data prevents sharing that data with other “databases”

Think of all the “databases” that lists your name, department, etc.:

• Messiah College Phone List Database• Students Using College Networked Computers• Students Using Dining Facility• Students Using Nursing Facility

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Database Management SystemDatabase Management System

Computer program designed to help a user store and retrieve data– Access, Oracle, DB2

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abcd 1234 123asd 123 12kghb 112 34

DBMSDBMS


tables

forms

query


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reports

labelsData

Dictionary

Outside Applications

DBMSEngine

attached

import

The Traditional versus the Database The Traditional versus the Database Approach to Data ManagementApproach to Data Management

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Fig 5.3Fig 5.3

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Problems with the “Traditional” Problems with the “Traditional” ApproachApproach

Data redundancy Program-data dependence Inflexibility

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Fig 5.4Fig 5.4

Data Modeling & Database ModelsData Modeling & Database Models

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Data Design IssuesData Design Issues

Content: What data should be collected? Access: What data should be given to what

users? Logical structure: How will the data be

organized to make sense to a particular user? Physical organization: Where will the data

actually be located?

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Data ModelingData Modeling

Logical designPhysical designPlanned data redundancyData model

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Data ModelsData Models

Hierarchical modelsNetwork modelsRelational models

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Fig 5.6Fig 5.6

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Fig 5.7Fig 5.7

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Fig 5.8Fig 5.8

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OperationsOperations

Select rowsProject columnsJoin tables

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Fig 5.9Fig 5.9

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Object-Relational Database Object-Relational Database Management SystemsManagement SystemsStores objectsHypertextHypermediaSpatial data technology

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Database Management Systems Database Management Systems (DBMSs)(DBMSs)

Provide a user viewProvide tools to create & modify the

databaseStore & retrieve dataManipulate dataProduce reports

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Selecting a DBMSSelecting a DBMS

Number of concurrent users Database sizePerformanceIntegrationFeaturesVendorCost

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Database DevelopmentsDatabase Developments

Data warehousesData martsData miningOnline analytical processing (OLAP)

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What Is a Database?What Is a Database?

Database: a collection of dataTable: the primary element for collecting

data, organized into rows and columnsRecord: an individual entry in a table (row)Field: a piece of data in a record (column)

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Access97: A Database ExampleAccess97: A Database Example

Field (column)

Record(row)

Table

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Access Database ObjectsAccess Database Objects

Table: Used to store and manipulate data.Query: Used to retrieve information.Form: Used to view one record of data.Report: Used to present, calculate,

summarize, and print table data.Macro/Module: Used to automate

frequently performed procedures.

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The database window is the command center; it provides the means to create, view, and edit database objects, such as tables, forms, and reports.

Controlicon

Objecttabs Processing or

Command Buttons

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What is the difference between a database and a spreadsheet?

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Cost Per Month

Videos Music CDs TotalSusie 42 25 67Jacob 38 36 74Total 80 61 141

Use Microsoft Excel to analyze financial and statistical data.

Excel Spreadsheet

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Use Microsoft Access to create, maintain, and summarize very large quantities of data.

Access Database

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Why do “databases” in spreadsheets?Why do “databases” in spreadsheets?

Because we canWe use 1 or 2 massive tables

– “Lots of tables make the database complex”– Discomfort with databases and multiple tables

Because we “think it’s simple”– Skip organizing the data into relational tables– Go straight to designing forms

NAME POSITION SPOUSE CHILDREN PHONE

Jones Chief Gloria, Karen 3274

Smith Clerk Betty 3241

Jones Chief Mary Glorai, Karen 3296

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Data Redundancy ProblemsData Redundancy ProblemsRedundancy breeds errors

– Same data defined in multiple places is BAD– Spelling/typographical error prone– Lack of data integrity

Inability to perform simple queriesInflexibility and inscalabilityImpossible to MAINTAIN!

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Relational DatabaseRelational DatabasePROJECTCHIEFProject Project ChiefComputing 333-22-1111Intranet 987-65-4321Contracting 123-45-6789Jordan 333-22-1111

DEPARTMENTSDept Dept. Director RoomEngr 181-94-5676 B115Math 987-65-4321 123M&B 123-45-6789 147

EMPLOYEESLName FName SSN DeptJones Mike 123-45-6789 M&BSmith Tony 987-65-4321 MathLee Bruce 567-89-1234 EngrrDoodle Yankee 333-22-1111 M&B

1

1

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ExampleExample

EmployeeSSNL NameF NameRankSpouseChildrenOffice Phone#Home Phone#Office Room#Dept Dept. Chief

EmpProjProject NameEmployee SSN Function

•Must know all constraints on data–project name is unique

–only one chief per project

–employees can have more than one phone#

–employees can have only one office

–many employees can use the same office

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Just a ReminderJust a Reminder

A table is a single object within a databaseA database can have other objects such as

queries, forms, reports, macros, and programming modules

However, at least one table object must be created before you can create any other type of object

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Database Design TemplatesDatabase Design Templates

CHOOSE: File, New Database orCLICK: New Database button

DesignTemplates

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Using Datasheet View (Usually used for entering data into records)

Using the Table Wizard (Usually used for creating tables)

Using Design View (Usually used for creating tables and editing fields)

How Do I Create a Table?How Do I Create a Table?

Sample Table in Datasheet View

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Using the Table WizardUsing the Table Wizard

Pick fields from existing business and personal table structures

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Using Design ViewUsing Design View

Specify field names, data types, and indexes from scratch

Define fieldsand data types

Define fieldproperties

Note: Fields are shown in rows in the design view,

not in columns.

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Field Data TypesField Data Types

Text Memo Number Date/Time Currency

Autonumber Yes/No OLE Object Hyperlink Lookup Wizard

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Field PropertiesField Properties

Field Size Format Decimal Places Input Mask Caption Default Value

Validation Rule Validation Text Required Allow Zero Length Indexed

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Primary Keys Primary Keys (Are extremely important in databases.)(Are extremely important in databases.)

Primary key is a field that uniquely identifies each record in a table– Data is automatically displayed in the datasheet sorted

by the primary key.– There are 3 types of primary keys: AutoNumber,

Single-Field, and MultiField.– You can use Access AutoNumber as a primary key

(since it is unique) but it is not a good idea.

CHOOSE: Edit, Primary Key orCLICK: Primary Key button

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Primary KeysPrimary Keys

A primary key is one or more data fields (columns) that uniquely identify each record in the table

What would the primary key be below?– “table of employees, assigned to a department.”

EMPLOYEESLName FName SSN DeptJones Mike 123-45-6789 MathSmith Tony 987-65-4321 M&BLee Bruce 567-89-1234 Science

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IndexesIndexes

Like Primary Key, can be used to determine the order in which data is displayed

CLICK: Indexes button

PrimaryKey

IndexDefinition

Indexes can slow down data entry. Access automatically creates indexes for fields with ‘ID’ in their names.

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Access Uses Automatic Saving Access Uses Automatic Saving

CLICK: a cell using the mouse pointerMake changes to the cell’s information.SELECT: another record to save the

changesCHOOSE: Edit, Undo from the menu

if you want to reverse the most recent changes

Note: This is a very important difference between Access and other Office 2000 products..

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Customizing Datasheet ViewCustomizing Datasheet View

Remember: formatting changes are not saved automatically. Only structural and data changes are saved automatically.

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Adjusting Row HeightsAdjusting Row Heights

DRAG: the border between rows to change all row heights in the datasheet

RowBorders

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Reordering FieldsReordering Fields

SELECT: the entire field columnDRAG: field name to move the column

To save the Datasheet view:CLICK: Save button

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Sorting RecordsSorting Records

Allows you to better organize and present data; makes information out of raw data (alphabetical phone listing)

SELECT: column or field to sortCLICK: Sort Ascending buttonCLICK: Sort Descending button

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FiltersFilters

Lets you limit the display of records in a table using a simple matching criterion

Methods for filtering data: Filter For Input Filter By Selection Filter Excluding Selection Filter By Form Advanced Filter/Sort

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What Is a Query?What Is a Query?

A query is a question you ask of your database– How many customers live in Chicago?– What is the average age of our employees?

There are two types of queries– Select queries let you retrieve information– Action queries let you modify information

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Queries versus FiltersQueries versus Filters

Although similar to filters, queries provide additional functionality:– you can display data from multiple tables– you can control which fields display– you can perform calculations on field values

While filters are temporary, queries are saved as independent database objects

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Query Design WindowQuery Design Window

A graphical query-by-example tool.

Displays tableson which you’vechosen to base

your query

Displays the gridthat you use to

specify your criteriaand sorting options

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Query Grid AreaQuery Grid Area

Field: used to add a field to the gridTable: used to clarify the field’s tableSort: used to sort the resulting tableShow: used to hide or show the fieldCriteria: used to set the query criteriaOr: used to specify a second criterion

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Specifying a Search CriteriaSpecifying a Search Criteria

Enter an example of value you are searching for in the Criteria row

Use the question mark (?) wildcard to represent a single unknown character

Use the asterisk (*) wildcard to represent more than one character

Use operators (<, >, =) to limit records between a range of values or dates

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Examples of Search CriteriaExamples of Search Criteria

Like Sm?threturns records with Smyth and Smith

Like Ch*ngreturns records with Chang and Chickering

Between 21 And 65returns records with values from 21 to 65

<=98000returns values of less than or equal to 98000

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How Do I Create a Form?How Do I Create a Form?

Using the AutoForm WizardUsing Design View

A form created usingthe AutoForm Wizard

Form Navigation Controls

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What Is a Report?What Is a Report?

An on-screen or printed display of organized data from a table

Examples include: sales summaries, invoices, mailing labels, personal address books, and inventory listings

Report Title

Name Address Phone

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AutoReport: ColumnarAutoReport: Columnar

Created using the AutoReport Wizard.

FieldNames

TableData

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AutoReport: TabularAutoReport: Tabular

Created using the AutoReport Wizard.

FieldNames

TableData

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Questions to consider when Questions to consider when designing a DataBasedesigning a DataBase

Who will use it?What type of tasks?What are the data sources?What output is required?

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Data ModelingData ModelingDetermine Data RequirementsDetermine Data Requirements

•Entity Class•something that can be identified in environment•each entity class is a separate table•each entity becomes a separate row in a table

•Attributes•property or characteristic of entity•each characteristic of an entity class become a column•each characteristic of an entry become an entry in table

•Keys •one or more attributes that uniquely identified an entity

•Constraints•values or rules the DBMS must enforce

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Designing a DatabaseDesigning a Database

Determine your output requirementsDesign your database on paper firstDivide information into separate fieldsDivide information into separate tables Identify each record with a unique codePlace important fields at top of structureTest your database

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Access Lab and AssignmentAccess Lab and Assignment If not familiar with Access, then go to lab and on course

web space do either Access 97 or Access 2000 tutorials.– access_tutorial_2000.html– access_tutorial_97.html

Try doing exercises 1-5 and 20-25 on page 205 and 206 using c05Ex15.mdb and Rolling Thunder Database from student CD (or from G:\Courses\Infsy540).

Database Assignment will be on course web space next week– dbms_assignment.html– Due by beginning of class on Oct 17th

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Questions?Questions?