Transcript Intro to the AS/400 - Florida State College at Jacksonville

Intro to Info Tech
Database Management
Systems
This presentation can be viewed on line at:
Copyright 2003http://web.fscj.edu/Janson/cgs1060/wk08.DBMS.ppt
by Janson Industries
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Objectives

Explain
 Data
as a resource
 Basic
DB concepts
 Files,
 Data
Tables, Records Fields, Keys
relationships
 Common
DBMS functions
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The Evolving Value of Data

Increase efficiency

Business requirement

Added value
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Good Information Qualities

Accurate

Timely and accessible

Organized for need
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Why Databases?

Before DB there were files
 Finance
created customer file
 Marketing, shipping, etc.

Results in
 Poor
accessibility: files on different
computers
 Marketing
updates don't update finance
and shipping data
 Duplicate
data between files
 Extra
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space
 Longer to update
 Greater chance of error
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Database



A structure that organizes data
into more efficient groups
DB consists of related groups of
data
Ex. create common Customer file
and relate Marketing, Finance &
Ship files
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Databases


Different DB types call these
groups different things
 File
Relation
Table
 Record
Tuple
Row
 Field
Attribute Column
DB types
 Hierarchical
 Relational
 Object-oriented

But all duplicate functions of others
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The Data Hierarchy

Field/Column

Has a unique name, size, and type

Record/Row

File/Table

Database

Keys
– ids each record
 Composite
 Foreign – relates tables
 Primary
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8
DBMS

Allows users to
Define
fields
Group into records
Define keys
Relate tables/files
Insert, change, and delete
records of data

Also provides
Data
integrity
Security
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9
Table Relationships

Defined by the relationship's
 Number
 Direction

of access
The number of the relationship
 For
a record in one table are
there one or many related records
in the other table
 1:1, 1:M, M:M

The direction of access
 Unidirectional,
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Bidirectional
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DBMS

When a record is deleted not
really deleted
 Marked

for deletion – why?
Data integrity: validating
 When
entered best time
– month, day, gpa
 Correct type entered – four vs. 4
 Consistent – customer id in DB
 Complete – zip code
 Range
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Other DBMS Functions

Query: retrieve and organize data
 Language:
SQL
 GUI: wizards

Reports
 Format

query results
Forms
 Easier
to enter data
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Other DBMS Functions

Backup
 Can

define a schedule
Recovery
 Transaction

journaling
Security
 Restrict
access by DB, individual
files, records or fields by user id
 Essentially creating alternative
views of the data
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DBMS Software

Lots of vendors
 Software
companies that create
and sell DBMSs

Lots of different DBMS s/w
 Even
MS has two: Access and
SQL Server
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DB Administration

DB Analyst (DA) designs DB
 Interviews
users
 Defines fields & groups into tables
 Defines keys & table relationships

DB Administrator (DBA)
implements and maintains DB
 Uses
DBMS to create DB
 Monitors performance
 Insures backup and recovery
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Points to Remember

DB at the heart of all large apps
 Grocery




checkout, Google, ATMs
DB fails, application fails
Variety of DB types and many DBMS
vendors
DBMS provides functions to create,
monitor, and protect DB
DBA and DA paid well
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