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0. Chapter 5. Database Concepts. Why Study Databases?. All most all Information Systems use an underlying Database to store information Because Databases are v astly superior to spreadsheets and file processing systems. Why Study Databases?.

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Chapter 5

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Chapter 5

Database 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

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

  • A field is an attribute of an entity


Records

  • A bunch of fields form a record

  • A record is an entity


Tables

  • A bunch of records forms a table

  • A table is a group of related entities


0

Databases

  • A bunch of tables form a database

  • A database can represent a single business or an entire market


0

Databases

  • But, databases are not just a bunch of tables

  • A database also includes relationships between the different tables


ThingA

ThingB

Relationship

Man

Woman

Married

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.


Student

Faculty

Student

Student

Advises

Get Advisement

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


Student

Course

Student

Student

Course

course has a student

Student

student takes course

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.


How to Model Relationships


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.


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