Introduction to Database
Changes and new experience make life delightful.
Unanimous
Data and Information
How are data and information related?
Next
processing
data stored on diskStep 1. The member data, including a photograph, is entered and stored on the hard disk.
Step 2. The computer extracts the member data from disk.
Step 3. The receipt is created and printed.
Data is raw facts Information is data that is organized
and meaningful
receipt
Computers process data into information
Add, change,
and delete data
Add, change,
and delete data
CreatedatabaseCreate
database
Sort and
retrieve data
Sort and
retrieve data
Createforms and
reports
Createforms and
reports
Data and Information
What is a database?
Next
Database software allows you to
Database software allows you to
Collection of data organized so
you can access, retrieve, and
use it
Collection of data organized so
you can access, retrieve, and
use it
Database software also called database management system
(DBMS)
Database software also called database management system
(DBMS)
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.
Creating the Database
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.
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.
There are three types of binary relationships: In a 1:1 (one-to-one) relationship, a single-entity
instance of one type is related to a single-entity instance of another type.
In a 1: M (one-to-many) relationship, a single-entity instance of one type is related to many-entity instance of another type.
In a M:M (many-to-many) relationship, a single-entity instance of one type is related to many-entity of another type and vice versa.
Entity- relationship diagram model
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
Non-normalized relation
Normalized relation
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.
The Hierarchy of Data
What is a hierarchy?
Next
Database contains files, file contains records, record contains fields, field contains characters
The Hierarchy of Data
What is a field?
Next
Combination of one or more characters
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
Yes/NoYes/No(also called Boolean)
—only the values Yes or No (or True
or False)
HyperlinkHyperlinkWeb address that links to document or Web page
ObjectObject(also called BLOB for binary large object)—photograph, audio, video,
or document created in other application such as word processing or spreadsheet
The Hierarchy of Data
What are common data types?
Next
CurrencyCurrencydollar and cent amounts or
numbers containing decimal values
DateDatemonth, day, year, and
sometimes time
MemoMemolengthy text entries
TextText(also called
alphanumeric)—letters, numbers, or special
characters
NumericNumericnumbers
only
AutoNumberAutoNumberunique number automatically assigned to each new record
The Hierarchy of Data
What is a record?
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Group of related fields
Key field, or primary key, uniquely identifies each record
The Hierarchy of Data
What is a data file?
Next
Collection of related records stored on disk
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
Isolated data—data stored
in separate files so it is difficult to
access
Isolated data—data stored
in separate files so it is difficult to
access
File Processing Versus DatabasesWhat is a file processing system?
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Data redundancy—
same fields stored in
multiple files
Data redundancy—
same fields stored in
multiple files
Each department or
area within organization
has own set of files
Each department or
area within organization
has own set of files
May have weaknessesMay have
weaknesses
Records in one file may not relate to
records in any other file
Records in one file may not relate to
records in any other file
File Processing Versus DatabasesWhat is the database approach?
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Many programs and users can share data in database Secures data so only authorized users can access
certain data
File Processing Versus DatabasesWhat are the strengths of the database approach?
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Reduced data
redundancy
Reduced data
redundancy Improved data
integrity
Improved data
integrityShared
dataShared
dataEasier accessEasier access
Reduced development
time
Reduced development
time
File Processing Versus DatabasesHow do a database application and a file processing application differ in the way they store data?
Next
Database Management Systems
What are popular database management systems (DBMSs)?
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Personal computer, midrange server, mainframe
IBM CorporationDB2
Personal computer, midrange server, mainframe
IBM CorporationInformix
ServerMicrosoft CorporationSQL Server
Personal computer, midrange server, PDA
Sybase Inc.Sybase
Personal computer, midrange server, mainframe, PDA
Oracle CorporationOracle
Personal computer, midrange server, mainframe
Computer Associates International, Inc.
Ingres
Personal computer, server, PDAMicrosoft CorporationAccess
Computer TypeManufacturerDatabase
Database Management Systems
What is a data dictionary?
Next
Contains data about each file in database and each field within those files
Database Management Systems
What is Structured Query Language (SQL)?
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Allows you to manage, update, and retrieve data Has special keywords and rules included in SQL
statementsSQL statement
SQL statement results
Database Management Systems
What is a query?
Next
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
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.
Database Management Systems
What is a query by example (QBE)?
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Program retrieves records that match criteria entered in form fields
Query by example screen
criteriaQuery results
Has a graphical user interface that assists users with retrieving data
Database Management Systems
What is a form?
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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
Database Management Systems
What is a report generator?
p. 532 Fig. 10-16 Next
Allows user to design a report on screen, retrieve data into report design, then display or print reports
Also called report writer
What is a data model?
p. 534 Fig. 10-18 Next
Rules and standards that define how database organizes data
Defines 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
DATA MODELS FOR POPULAR DBMSs
Data model
Relational database
What is a relational database?
Next
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
DATA TERMINOLOGY
Relational database
What is a relationship?
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Connection within data
Hierarchical database model rigidly 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.
The strongest advantage of the hierarchical database approach is the speed and efficiency with which it can be searched for data.
The hierarchical model does have 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.
Hierarchical Database Model
Hierarchical Database model
Data model that creates relationships among data in which subordinate records can be linked to more than one data element.
Network Database Model
Advantages and Disadvantages of Logical Data Models
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 withhierarchical 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 Data Models
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.
Specialized Database Models
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.
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.
What is an object-oriented database (OODB)?
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Advantages
Often uses object query language (OQL)
Stores data in objectsObject is item that contains data, as well as actions that read or process data
Can store more types of dataCan access data faster
What are examples of applications appropriate for an object-oriented database?
Next
Multimedia databasesMultimedia databases
Store images, audio clips, and/or video clips
Store images, audio clips, and/or video clips
Groupware databasesGroupware databases
Store documents such as schedules, calendars, manuals,
memos, and reports
Store documents such as schedules, calendars, manuals,
memos, and reportsComputer-aided design (CAD) databasesComputer-aided design (CAD) databases
Store data about engineering, architectural,
and scientific designs
Store data about engineering, architectural,
and scientific designs
Hypertext databasesHypertext databases
Contain text links to other documentsContain text links to other documents
Hypermedia databasesHypermedia databases
Contain text, graphics, video, and sound
Contain text, graphics, video, and sound
Web databasesWeb databases
Link to e-form on Web pageLink to e-form on Web page