Databases Chapter 11. 11 Chapter 11: Databases2 Chapter Contents Section A: File and Database Concepts Section B: Data Management Tools Section

DatabasesDatabases

Chapter 11Chapter 11

Chapter 11: Databases 2

11 Chapter Contents

Section A: File and Database Concepts Section B: Data Management Tools Section C: Database Design Section D: SQL Section E: Database Security


11SECTION A

File and Database ConceptsFile and Database Concepts Database Basics Database Models


11 Database Basics A database is a collection

of information– Typically stored as computer

files

The tasks associated with creating, maintaining, and accessing the information in databases are referred to as data managementdata management, file management, or database management


11 Database Basics

Databases can be used in a variety of ways– Collect and store data– Update data– Organize and

output data– Distribute data– Find data– Analyze data


11 Database Basics

Data miningData mining refers to the process of analyzing existing information in databases to discoverdiscover previously unknown and potentially useful informationuseful information, including relationships and patterns– Data warehouse– Predictive analytics


11 Database Models

An unstructured fileunstructured file has a unique structure A structured filestructured file uses a uniform format to

store data The underlying structure

of a database is referred to as a database modelmodel


11 Database Models

The simplest model for storing data is a flat flat filefile that consists of a single, two-dimensional two-dimensional tabletable of data elements

Records can be displayed as rows in a table or as forms.


11 Database Models

A fieldfield contains the smallest unit of meaningful information

Each field has a unique field namefield name Variable-lengthlength field vs. fixed-length field


11 Database Models

A recordrecord is a related collectionrelated collection of data fields The templatetemplate (blank form) for a record is

referred to as a record type A record that contains data is referred to as a

record occurrenceoccurrence


11 Database Models

A relationshiprelationship is an associationassociation between data that is stored in different record types– One-to-many– Many-to-many– One-to-one


11 Database Models

A hierarchical databasehierarchical database arranges record types in a hierarchy


11 Database Models

The network databasenetwork database model allows many-to-many relationships in addition to one-to-many relationship


11 Database Models

A relational databaserelational database stores data in a collection of related tablesrelated tables

Much more flexibleflexible than hierarchical or network models.


11 Database Models

A (multimulti)dimensional databasedimensional database organizes relationships over three or more dimensions

Easy to maintain.

Data is stored in a structure related to its use.

Used primarily for data analysis and decision support systems.


11 Database Models

An object (object-oriented) databaseobject (object-oriented) database stores data as objects, which can be grouped into classes and defined by attributes and methods


11 Database Models An object-relational object-relational

databasedatabase is used to describe a variety of technologies that combine object-oriented and relational concepts


11SECTION B

Data Management ToolsData Management Tools Data Management Software Database Management Systems Databases and the Web XML


11 Data Management Software

Microsoft Word Microsoft Word allows you to create a “flat” table of information, such as a mailing list, which you can edit, sort, search, and print. In addition, you can merge data from the table with a template letter to create form letters, mailing labels, and envelopes.



MS ExcelMS Excel



It is possible to enter data as ASCII text file Custom data management software Data dependenceData dependence vs. data independencedata independence


11 Database Management Systems

Software packages Software packages designed to manage data stored in a database– XML DBMS (primarily for use on the Web)– OODBMS (object-oriented DBMS)– RDBMS (Relational DDMS - often include tools

to deal with XML and object-oriented data)



An entry-level DBMS,like Microsoft AccessMicrosoft Access,usually includes all thetools you need to manipulate data in a database.



Database client softwareDatabase client software allows a remote computer or network workstation to access data in a remote database (database server)



Multiple users can interact with the same database


11 Databases and the Web

The Web provides opportunities and challenges for accessing databases– StaticStatic Web publishing (read-only snapshot of

data)– DynamicDynamic Web publishing (script-driven, on-the-fly

view of data)• Server-side program




11 Databases and the Web FormsForms can

collect datacollect data for database update,as well as specifications for a queryquery– XFormsXForms: an

alternative to HTML forms



Several tools are available to help create server-side programs

ASP: Active Server Pages (Microsoft)CGI: Common Gateway Interface (standard)PHP: Hypertext Preprocessor


11 XML Documents

Markup languageMarkup language allows field tags, data, and tables to be incorporated into a Web document


11 XML Documents Used to specify a standard structurestandard structure of fields

and records Data in an XML document is searchable searchable via

XML query engines (XPath, XQuery) XML is portableportable, but not optimized for many

common database operations– Consider storing data in a relational database,

managing it with RDBMS software, and generating XML documents for exchanging data over the Web


11SECTION C

Database DesignDatabase Design Defining Fields Normalization Organizing Records Designing the Interface Designing Report Templates Loading Data


11 Defining Fields The term database structuredatabase structure refers to the

arrangement of fields, tables, and relationships in a database

Example: Storing last names and first names in separate fields

Use a primary keyprimary key field to make each record unique unique (e.g., your student id #)

Use appropriate data types for each field (e.g., store numbers as numbers, not text)


11 Defining Field

Some Basic Data TypesData Types:


11 Defining Fields A computed (calculated, derived) fieldcomputed (calculated, derived) field is a

calculation that a DBMS performs during processing and stores temporarily

Uppercase and lowercase are not always treated the same– Case sensitive database

Field formats show what the data is supposed to look like when it’s entered

Field validation rulesField validation rules are used to filter data


11 Normalization

Process that helps save storage space and increase processing efficiency– Reduces data redundancyReduces data redundancy

Notice that in this example, there is no need to carry complete customer info in each record for every order.


11 Organizing Records Records can be organized in different ways,

depending on use Sorting

– A table’s sort ordersort order refers to the order in which records are stored in the database

– The sort key sort key is the field that is used to determine the sort order

Indexing– Refers to an index numberindex number for the record for each sort

key– Similar to the index in a book (“where do I find….?”)


11 Organizing Records

When indexed by date, the index file contains a list of keys and the record number (R#) that contains more information about the album released on that date.


11 Designing the Interface

Arrange fields in a logical orderlogical order Provide visual cluesvisual clues to the entry areas Entry areas should appear in a consistent

positionposition relative to their labels Provide a quickquick way to move through the

fields in order



Use scrollingscrolling or create multiple screens, if necessary

Provide buttonsbuttons or other easy-to-use controls for navigating through records

Supply on-screen instructionsinstructions




11 Designing Report Templates

Report generators are used to specify the content and format for a database report

A report template contains the outline or general specifications for a report


11SECTION D

SQLSQL SQL Basics Adding Records Searching for Information Updating Fields Joining Tables


11 SQL Basics

Intermediary between the database client software and the database itself– Query language

SQL: Structured Structured Query LanguageQuery Language


11 SQL Basics

Some Basic SQL Commands:


11 Adding Records


11 Searching for Information

SELECT AlbumTitle, AlbumCover FROM Albums

WHERE ArtistName = ‘Jefferson Airplane’

The AND, OR, and NOT Boolean operatorsBoolean operators are used to perform complex SQL searches

The use of parenthesesparentheses indicates the part of the query to perform first (specifies precedence of operations)


11 Updating Fields

UPDATE Albums

SET InStock = InStock – 1

WHERE AlbumTitle = ‘G.I. Blues’

Global updatesGlobal updates change the data in more than one record at a time– Works only for records with similar characteristics


11 Joining Tables

Joining tables in SQL allows you to create relationships between tablesrelationships between tables


11 Joining Tables

SELECT Albums.AlbumTitle,Albums.AlbumCover,Albums.DiscountPrice,Tracks.TrackTitleFROM Albums JOIN Tracks onAlbums.Cat# =Tracks.Cat#WHERE Album.Cat# = ‘LPM-2256’

Chapter 11 CompleteChapter 11 Complete

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