Download Document

Chapter 5
Database Concepts
Why Study Databases?

Databases have incredible value to businesses.




Very important technology for supporting operations.
Vastly superior to spreadsheets and file
processing systems
Businesses cannot survive without secure,
accessible, and flexible data.
Database provide a universal standardized way
to store data (in a secure way).
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
Large
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
Small
Fields

Characters “B R E I M E R” form a field
Last Name
Breimer

A field is an attribute of an entity
Records


A bunch of fields form a record
First Name
Last Name
Sex
Eric
Breimer
Yes
A record is an entity
Weight
263
Tables


A bunch of records forms a table
First Name Last Name
Sex
Age
Eric
Breimer
M
46
Joseph
Kim
M
20
Allie
Primo
F
21
A table is a group of related entities
Databases

A bunch of tables form a database
Order Table
Customer Table
Product Table

A database can represent a single
business or an entire market
Databases

But, databases are not just a bunch of
tables
Orders
OID
CID
PID
Quantity
001
508
199
500,000
002
508
201
2
003
510
201
1
Customers

Products
CID
FName
LName
Address
PID
Description
Cost
508
Eric
Breimer
...
199
Viagra
$45.99
509
Andrew
Zych
...
200
Tooth Paste
$2.58
510
Greg
Smith
...
201
Hair Gel
$5.99
A database also includes relationships
between the different tables
Chapter 5
Relationships & Queries in
Databases
Types of Relationships
ThingA
One to One
 Examples?
 Analysis Technique




ThingB
Relationship
Man
Woman
Married
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.
Types of Relationships
Student
Faculty
One to Many
 Examples?
 Analysis Technique




Student
Student
Advises
Get Advisement
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
Types of Relationships
student takes course
Student
Many to Many
 Examples?
 Analysis Technique




Course
Student
Course
Student
Student
course has a student
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.
How to Model Relationships
Orders
OID
CID
PID
Quantity
001
508
199
500,000
002
508
201
2
003
510
201
1
Customers
Products
CID
FName
LName
Address
PID
Description
Cost
508
Eric
Breimer
...
199
Viagra
$45.99
509
Andrew
Zych
...
200
Tooth Paste
$2.58
510
Greg
Smith
...
201
Hair Gel
$5.99
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 –


Lack of Integration –


duplicate data requires
update to many files
data stored in
separate files
hard 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.