Chapter 5 Database Concepts
Mar 15, 2016
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.