Chapter 5

Chapter 5Database Concepts

Why Study Databases?

All most all Information Systems use an underlying Database to store information

Because Databases are vastly superior to spreadsheets and file processing systems

Why Study Databases?

Databases have NOT changed much in almost 40 years. Because it is a great framework for storing data

Overtime, the entire world has embraced the same standard framework Databases will not go away anytime soon.

Foundation Data Concepts

Abstract Concepts Entity – person, place, object or event

– stored as a record or a table row

Attribute – characteristic of an entity

– stored as field or table column

Foundation Data Concepts

Database Concepts Database – a collection of related tables Tables – a collection of related records

– collection of related entities Record – collection of fields (table row)

–represents an entity Field – collection of characters (table column)

– represents an attribute Character – single alphabetic, numeric or other symbol

Large

Small

Fields

Characters “B R E I M E R” form a field

A field is an attribute of an entity

Last Name

Breimer

Records

A bunch of fields form a record

A record is an entity

Last Name

Breimer

First Name

Eric

Sex

Yes

Weight

263

Tables

A bunch of records forms a table

A table is a group of related entities

First Name Last Name Sex Age

Eric Breimer M 46

Joseph Kim M 20

Allie Primo F 21

Databases

A bunch of tables form a database

A database can represent a single business or an entire market

Customer Table

Product Table

Order Table

Databases But, databases are not just a bunch of

tables

A database also includes relationships between the different tables

CustomersCID FName LName Address508 Eric Breimer ...

509 Andrew Zych ...

510 Greg Smith ...

ProductsPID Description Cost199 Viagra $45.99

200 Tooth Paste $2.58

201 Hair Gel $5.99

OrdersOID CID PID Quantity001 508 199 500,000

002 508 201 2

003 510 201 1

Types of Relationships

One to One Examples? Analysis Technique

Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If the two answers are NO, then it is a one to one

relationship.

ThingA ThingBRelationship

Man WomanMarried

Types of Relationships

One to Many Examples? Analysis Technique

Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If only one answer is yes, then you have a one to

many relationship

FacultyStudentStudentStudent

Advises

Get Advisement

Types of Relationships

Many to Many Examples? Analysis Technique

Consider ThingA and ThingB Can ThingA be related to more than one ThingB? Can ThingB be related to more than one ThingA? If the answers are yes and yes, then the relationship

is many to many.

course has a student

student takes course

CourseStudentStudentStudentCourseStudent

How to Model Relationships

CustomersCID FName LName Address508 Eric Breimer ...

509 Andrew Zych ...

510 Greg Smith ...

ProductsPID Description Cost199 Viagra $45.99

200 Tooth Paste $2.58

201 Hair Gel $5.99

OrdersOID CID PID Quantity001 508 199 500,000

002 508 201 2

003 510 201 1

Find the name and hire date of the manager working on the sales manual project

Traditional File Processing Sucks

File Processing: Data is organized, stored, and processed

in independent files of data records Sometimes the files are spreadsheets Sometimes they can can even be Word or

Text Documents (eeeck!)

Problems of File Processing Data Redundancy –

duplicate data requires update to many files

Lack of Integration – data stored in

separate fileshard to combine data

Data Dependence – changing the file format requires changing the

program…

Database Management Approach Consolidates data records into one CENTRAL

database that can be accessed by many different application programs.

Database Management Software (DBMS)

Definition: Software that controls the creation,

maintenance, and use of databases

DBMS Software Components

Database Definition Language and graphical tools to define

entities, relationships, integrity constraints, and authorization rights

Application Development Graphical tools to develop menus, data entry

forms, and reports

DBMS Software Components

Transaction Processing Controls to prevent interference from

simultaneous users and Controls to recover lost data after a failure

Database Tuning Tools to monitor and improve database

performance

Database Interrogation

Definition: Capability of a DBMS to report information from

the database in response to end users’ requests

Query Language – allows easy, immediate access to ad hoc data requests

Report Generator - allows quick, easy specification of a report format for information users have requested

Natural Language vs. SQL Queries

Schemas

Schema - A description of the database

Subschema – describes a subset of the database and which users have access to this subset

Data Definition Language

Language Used to describe Schemas and Subschemas

Describes relationships between different data

Provides a Logical view of the data

Data Dictionary Entry

A more detailed description of the data in a database

Specifies data types and ranges

Assists programmers in understanding the data

Physical vs. Logical

DBMS concentrate on Physical access to the underlying tables Concurrency control Query’s Creating/deleting

tables

Physical vs. Logical

MIS systems are (Logically) interface with a DBMS monthly reports charts automated inquiries

Application Development

Today, even non-technical staff can use tools to build little programs that use a database. Database Management Systems have all

kinds of tools to develop custom application programs and interfaces.

Example: The College’s MIS (Banner) is actually an application built on top of a Oracle Database.